pl | en

Phono stage

RCM Audio

Manufacturer: RCM AUDIO

Price (during test): 9000 PLN

ul. Czarnieckiego 17
40-077 Katowice | Polska


Provided for test by RCM S.C.

CM Audio is the production branch of a well-known Polish distributor, the RCM company. The company owner, Roger Adamek, is a fan of the analogue and he still believed in its importance at the time when even the most reasonable people got rid of their collections of black discs, buying the same records in a digital form. A lot of these people are buying the same records for the third time today, again on vinyl.

The first two products of RCM Audio, from eight years ago, were a reflection of Roger’s faith in vinyl and tubes – it was the Sensor Prelude IC phono stage and the Bonasus tube integrated amplifier (i.e. “stork”; its version in a red casing was also available). Both of them became pretty popular and have been appreciated all over the world.

It could be surprising that the “IC” was a semiconductor preamplifier, based on circuit boards. This is something that purists do not like. However, the effects spoke for themselves – in comparison, most tube preamplifiers sounded as if they were silted. The advantages of the “IC” were appreciated by journalists working for a lot of magazines all over the world, including me – the Sensor Prelude IC became part of my reference system for many years.

Nothing had been happening for a longer time in RCM Audio, until we got to know the THERIAA preamplifier. It was a much more expensive and much better product, but also based on integrated circuits. It also had an external power supply unit. Based on what was possible to achieve in the case of this product, the company has prepared a new, altered version of the Sensor, called Sensor2.


These are some of the changes that the RCM Audio company points out to:

  • a more powerful external power supply unit, with DC instead of AC voltage on the output,
  • greater filtering capacity in the power supply unit,
  • an enhanced amplifying and correction system, including the arrangement of components,
  • higher-quality integrated circuits, resistors and capacitors,
  • casing similar to the THERIAA casing, without visible screws,
  • more cartridge loading options,
  • a better earthing clamp.

Sensor2 is a MM/MC semiconductor phono stage (integrated circuits) with an external power supply unit. It offers amplification within the range of 0.3 mV to 5 mV, at 2 V (1 kHz) output voltage. It means that the maximum amplification is 76 dB. A change of load and amplification is carried out using miniature DIP switches located on the back panel. The device has a balanced input, while RIAA correction is unbalanced and the output is balanced – output signal can be collected from XLR or RCA sockets.

RIAA correction is passive, with two separate RC filters, low noise resistors and polypropylene capacitors of 1% tolerance. All the elements are hand-selected, measured and paired, which results in RIAA linearity of +/- 0.3 dB within the range of 20 Hz to 20 kHz.

There are a few additional options available for the preamp, just like for its previous version:

  • gold-plated Furutech input (RCA) and output (RCA, XLR) sockets,
  • an IEC power socket with a Furutech fuse,
  • rhodium-plated Furutech input (RCA) and output (RCS, XLR) sockets.

RCM Audio

The first version of the Sensor was created on the basis of experience gained while configuring analogue systems and looking for solutions that would be better and would suit our tastes better than the available ones. We were hoping that they would also suit the tastes of our clients. This resulted in the Sensor Prelude IC project. Considering that it was a project of a company that had not been associated with production before, the Sensor sold very well both in Poland and abroad. While it was being produced, a few changes were made to its construction, but they were not significant enough to make it possible to talk about a new version of the phono stage.

After six years, the time came to introduce more radical changes resulting from the experience gained while designing the THERIAA phono stage. The change that is visible straight away from the outside is the casing. The screws from visible planes are gone and the phono stage has become slightly bigger, but, which is most important, the casing has become more rigid. The changes “inside” are more important and they are mainly found in the power supply unit, but not only. The correction section has also been altered in a few ways. These are not just “cosmetic” changes – they have big influence on the sound of the device. So, this time we can talk about a new version of the phono stage. This is how the Sensor2 has been created.

The new Sensor’s power supply has been improved due to, among others, the use of a better transformer (Myra) having higher power and voltage. Rectification and the first stage of stabilization are now in the casing of the power supply unit. The second stage is located in the casing of the phono stage. Power supply entering the phono stage is already “rectified” and stabilized, which results in lower interference.
Low impedance Panasonic capacitors having a longer lifetime are used in the filtration system.
Low noise, precise resistors and Evox Rifa capacitors are used in the correction stage. All the important elements are hand-selected. The gradation of cartridge impedance matching has been slightly altered.

An ABA test was used to compare the phono stage to other devices (A and B known). The reference devices were the RCM Audio Sensor Prelude IC, the Amare Musica ASPIRIA, and, secondarily, all phono stages that I have tested in the last eight years – both in “High Fidelity” and “Audio”.
The preamp was placed on the Acoustic Revive RAF-48H platform, while the power supply unit – on the RST-38H platform. The power cable used was the Crystal Cable Absolute Dream.

RCM Audio in “High Fidelity”
  • REPORTAGE: „HOME, SWEET HOME…” a few words (and an interview) on the occasion of opening the new headquarters of the RCM company , read HERE
  • TEST: RCM Audio THERIAA – phono stage, read HERE
  • TEST: RCM Audio SENSOR PRELUDE IC – phono stage, read HERE
  • TEST: RCM Audio BONASUS – integrated amplifier, read HERE

  • Recordings used during the test (a selection):

    • Bill Evans, Selections from Live at Art D'Lugoff's Top Of The Gate, Resonance Records HLT-8012, “Limited Edition #270”, Blue Vax 10” LP (2012).
    • Dire Straits, Brothers in Arms, Warner Bros./Mobile Fidelity Sound Lab MFSL-2-441, “Special Limited Edition No 3000”, 2 x 180 g, 45 RPM LP (1985/2014).
    • Frank Sinatra, The Voice, Columbia/Classic Records CL 743, “50th Anniversary”, Quiex SV-P, 180 g LP (1955/2005).
    • Jean-Michel Jarre & Tangerine Dream, Zero Gravity, The Vinyl Factory VF184, 45 RMP, 180 g LP (2015).
    • Julie London, Julie is Her Name. Volume Two, Liberty/Analogue Productions APP 7100, 180 g LP (1958/2014).
    • Tsuyoshi Yamamoto Trio, Midnight Sugar, Three Blind Mice/Cisco TBM-23-45, “Twenty-Fift Anniversary Limited Edition, No. 0080/1000”, 45 RPM, 2 x 180 g LP (1974/2004).
    Japanese CD editions are available from

    Testing a product which has replaced an element that is part of the editorial staff’s reference system in a given manufacturer’s offer is something completely different than an “ordinary” test. The procedure is, naturally, the same, it is never altered, but the expectations are completely different. It is because the device, speakers, cables, etc., usually used for years to evaluate other products, are thoroughly known to the journalist who uses them – he or she knows both their advantages and disadvantages. Since we are talking about a reference system, it is clear that the given product has not been placed there by accident – it has been selected due to its high sound quality, functionality and (often) its aesthetic qualities, as well as because of its “compatibility” with the rest of the system and with the journalist’s expectations.

    The Sensor Prelude IC phono stage has been in my system for eight years and, to be more precise, since October 2007 (its test was published in “High Fidelity” a month later). During this time, the whole world, just like Poland, has changed almost beyond recognition, while “High Fidelity” has changed its layout a few times, and the Sensor’s manufacturer has built new impressive headquarters.

    One thing has remained unchanged: the first phono stage offered by RCM Audio, although inexpensive and small, was an amazing tool for me, cooperating with such extremely expensive turntables as: the Transtoror Argos, the TechDAS Air Force One and the Two, as well as with some outstanding phono stages: the Vitus Audio SP-102, the Convergent Audio Technology SL1 Legend and the THERIAA – the more expensive RCM Audio phono stage.

    To say more, it has never let me down. I have heard in what ways more expensive, better devices are superior to it, but, frankly speaking, I have never felt “urged” to replace it. So, the test of the Sensor2 was, in the first place, a comparison with the Sensor Prelude IC for me, and only secondly a test as such.


    If something is good, it will always remain good – this is what I have always thought. The older Sensor is an example which confirms this rule. When we listened to it during the ABA test, it proved it is great. Not even for a moment did my face express discontent or disappointment. On the contrary, I was rather focused and attentive, as the constructors of the phono stage deserve the utmost respect.

    However, it was hard for me to think that nothing has changed. The new Sensor is better, in almost every respect. However, just like in the case of all the good products that I am talking about, these are deep evolutionary changes that develop the “superstructure” and not the “base”, if I may say so. It is very clear sound. It is something that surprises me every time I compare the Sensor to other phono stages (to their disadvantage). Only once another device proved to be better in this respect – and that was the THERIAA. It is all about giving out sounds in themselves, with other sounds, and not in a cluster under which there is something more, something that is hard to define.

    Thanks to the clarity, the tone, the dynamics and the sound stage are highly independent and wonderfully differentiated. I think that this is why the phono stage has such incredible resolution, without going into too much unnecessary detail.
    When the Sensor2 is compared to the first Sensor, one can notice a distinct change, but not as noticeable as in the case of the THERIAA. But also, as the tone range is a bit different in the Sensor2 and the “energetic” accents are distributed in a different way, it is closer to the top RCM Audio preamp than to its first version.

    The energy that I am talking about consists in saturating sound with rhythm and tangibility. Knopfler’s electric guitar on Brothers in Arms, Isoo Fukui’s bass guitar on Midnight Sugar and Marty Morell’s percussion on Bill Evans’s album were all stronger, denser and more “here and now”.
    One may perceive this change as slight darkening of the tone – it will be a justified assumption. However, it is worth taking into account that it is not about manipulating the tone. To me, the “less present” upper midrange rather means better saturation with harmonics and more “sound in sound”, which results in a very mature musical message.


    The tonal balance is, as for me, almost perfect. It was similar with the “IC”, but now, thanks to better differentiation, the perception of even those records that “have problems with the treble” is even more acceptable. Under unfavorable circumstances, the first Sensor could sound a little “light”. It was not its fault, but the fault of the surroundings, but that was the reality. The Sensor2 seems to be more resistant to these problems, entering sound more deeply and, thanks to this, “noticing” less of what is happening on the surface, i.e. technical problems. Expensive preamps, including the Vitus, have denser bass and more firmly “sit” on the base, although after accommodation to the character of the Sensor2 one does not have a problem with it.

    The sound stage is very broad and deep – it is something that makes RCM Audio phono stages different from all other preamps. Here, the space between us, the line connecting the speakers and the back of the stage is also more filled up. Also sounds BEHIND the listener, like on Roger Waters album, and Jarre and Tangerine Dream maxi-single, are more fleshy and explicit. I think that this is largely due to excellent resolution, as well as rhythmicity – the speed of the sound attack is immediate. So, nothing has changed: when one compares other, most frequently tube preamps to RCM Audio products, they all (I repeat: all, with full responsibility) sound as if the music was being played slightly more slowly, and as if warmth was taking over a large part of the information on the aura, surroundings, air and textures of the instruments themselves.

    It is very even, precise, but never unclear or harsh sound. The bandwidth edges are strong, explicit and precise. The bass is perfectly stretched and controlled, though the latter gives the Sensor Prelude the only (theoretical) advantage over the Sensor2. It is all about the fact that the Sensor Prelude’s mid-bass is a bit drier. Therefore, instruments operating within this range have a shorter decay, which is often welcomed, as most recordings fail us in this respect. As regards the Sensor2, nothing gets masked due to better filling, better fluidity of the range and, most of all, more explicit reverberation – so, we get more of what is actually recorded on the album.

    If I were to use some kind of a comparison, I would have to appeal to the sensitivity of those who swim. You can recognize a beginning swimmer by, among others, the fact that they try to stretch their arms as far as possible while swimming breaststroke, as it seems to them that in this way they will swim faster. This is how weaker preamps sound. An experienced swimmer uses their arms only to make short movements that actually aim to help him or her bring the head above the surface of water and enter the water again, while the whole body moves mostly due to the movement of legs – this is how the Sensor2 sounds. The top professionals know that legs have nothing to do with the breaststroke and make fast, short movements, keeping their knees together.


    The Senor2 is one of the best phono stages that I have ever heard. Of course, I am aware of the fact that its price is not high (as far as high-end is concerned), but it is what it is. We get distributive and differentiating, and therefore very colorful sound. It is also liquid and smooth – it is a considerable change when compared to the Prelude IC. Its greatest advantage is that it shows recordings in their full complexity – they are dense and deep, and they have the continuity that lets recordings become alive, as if they were breathing fully. If anything can be changed about it, that would be adding a little “foundation”. This is what the best and most expensive preamps that I know do. This does not exactly result in lowering the tone, but in greater volume, stronger “here and now”.

    It is a professional tool and an excellent supplement of even very expensive audio systems. It is clear that it is possible to achieve even better results, but, firstly, that means spending many times more money and, secondly, one would have to come to like it. RED Fingerprint.

    The Sensor2 phono stage is rather small and its circuits are located in two casings. In the larger one there are correction and amplification circuits, and in the smaller one there is the power supply unit. Both casings are rigid and made of thick aluminum – they have the shape of pipes with rectangular cross sections, into which boards are inserted. Similarly to the first version of the preamp, here the feet are also “symbolic”, having the form of rubber hemispheres. It seems that the manufacturer assumes that users will, anyway, place the preamp on feet that they trust. Both casings are very neatly and professionally made. Two color versions are available: one with a black and one with a silver front; the power supply unit is black in both cases.

    Phono stage

    There is only a green micro LED on the front panel of the preamp. Much more can be found at the back. There is an RCA input (balanced or unbalanced) – we choose the mode using a DIP switch. It is good to start with the balanced mode and switch to the unbalanced mode only when loud hum is present in speakers. There are two outputs – an unbalanced RCA output and a balanced XLR output. If there is a balanced signal on the input, it is transformed into unbalanced signal in the correction section anyway. The signal is balanced again in the output section. The sockets used in the preamp are Neutrik XLR sockets and Teflon Eagle-Cable RCA sockets. .

    There are DIP switches next to the sockets, separate for gain and impedance. Each channel has a set of two such switches. Impedance can be changed in eight steps: 20, 30, 50, 100, 200, 400, 1000 and 47 000 Ω, while gain – in seven: 0.3/0.4/0.6/0.9/1.4/2.5/5 mV. Next to the switches there is a ground terminal (which is not gold-plated) and an external power supply unit socket. It is better than in the previous version – it is a 5-pin Amphenol XLR socket.

    The electrical circuit is located on three boards – on one of them there is a symmetrical power supply (without a transformer) and on the remaining two there are correction and amplification circuits; each channel has its own PCB. It is a semiconductor circuit, based on integrated circuits: there is the Burr Brown INA217 circuit on the input and then the OPA2134 (produced by the same manufacturer). Next to the XLR output there is the Analog Devices SSM2134 circuit – a low-noise buffer which is usually used to send signal through long cables.

    There are precise, metalized resistors, Vishay capacitors and one big polypropylene Wima capacitor on the board. As regards the power supply board, there are two capacitor banks (22 capacitors altogether) and integrated stabilizers from the LM (317) series. It is good, clean work..

    Power supply unit

    The power supply unit is assembled in a similar way to the preamp, i.e. it is composed of aluminum elements. However, contrary to what the preamp looks like, here you can see screws at the front. It is a small black box with a permanently attached cable having an Amphenol XLR female connector at its end. It has an IEC power socket on the back panel, with a fuse and a mechanical power switch.

    Inside, there is a small classic transformer in a plastic casing, an EMI filter, a single LED-based bridge and two banks of filtering capacitors. The capacitors are bypassed with Evox Rifa capacitors with metalized polyester film. In the Prelude IC voltage was rectified in the preamp – here it is already rectified in the power supply unit.

    Technical specifications (according to the manufacturer):

    Input sensitivity: 0.3 - 5 mV (adjustable)
    Sensitivity adjustment options:
    0.3/0.4/0.6/0.9/1.4/2.5/5 mV 
    52 - 76 dB (2 V rms output)
    Input impedance:
    20 Ω, 47 000 Ω
    Impedance adjustment options:
    20, 30, 50, 100, 200, 400, 1000 and 47 000 Ω
    Input capacitance: 100 pF
    Input operation mode: symmetrical - unsymmetrical
    Input: RCA
    THD: 0.01%
    S/N: 85 dB
    RIAA linearity: +/- 0.3 dB (20 Hz – 20 kHz)
    Output impedance: 70 Ω
    Output: XLR, RCA
    Nominal output: 2 V rms
    Maximum output: 8 V rms

    245 x 227 x 110 mm – preamp
    122 x 230 x 70 mm – power supply unit

    3.5 kg - preamp
    1.7 kg – power supply unit

    Power consumption: max 17 W

    Bach To Moog
    Craig Leon | Jennifer Pike
    Sinfonietta Cracovia

    Music on Vinyl | Sony Classical MOVCL019

    Medium: 180 g LP
    Year of release: 2015

    The tradition of transcribing musical works for other instruments is as old as the history of music itself. At the beginning it was easy, in the sense that notation was not very precise and it was possible to perform given parts using different instruments, or even sing them (and vice versa) without too much difficulty.

    However, Bach to Moog belongs to a slightly different part of the musical heritage. It refers to the 1960s, when attempts were made to replace live instruments with their electronic equivalents. As opposed to transcription, it was all about rendering the sound of the original instrument as faithfully as possible. That was the idea behind the album Switched-on Bach released in 1968 by Columbia Masterpieces, on which Wendy Carlos played electronic instruments (let me remind you that an album entitled Bach Rewrite, recorded by Capella Cracoviensis with Orzechowski on a Rhodes piano and Masecki on a Wurlitzer piano, was released in 2012 by Decca).

    Referring to that event, Craig Leon, who plays a Moog analogue synthesizer, decided to celebrate the 50th anniversary of creating the first modular synthesizer of this type, and at the same time pay tribute to its creator, Robert “Bob” Moog (1934-2005) who died exactly ten years ago. He invited the violinist Jennifer Pike and the Cracovian orchestra Sinfonietta Cracovia to carry out his plan. The process of recording was divided into two stages: Craig recorded his parts in the Bottomwood Recording studio in Buckinghamshire, while the violin and orchestra were recorded in Alwernia near Cracow, in Alvernia Studios which looks like the alien town from Alien.


    The album was prepared by Atlas Realisation Music and the copyright was bought by Sony Classical which released the album together with Music on Vinyl. We know the latter company well – I wrote about it some time ago. I also regularly present albums that it publishes (more HERE).

    However, Bach to Moog is a unique album in its catalogue. This is the first album of the new Classical series, which will include recordings connected with classical music. Apparently, somebody has made an effort to make the series as attractive as possible. Instead of a plain envelope made of thin film, we get an excellent external envelope made of thick vinyl having a white vignette decorated with golden letters at the front, and a logo of the series stamped at the back. The disc is not put in an ordinary paper cover, but in a much better cover with antistatic film in the paper. It is a varnished gatefold cover with an insert and very nice photos which present the cosmic interior of Alvernia Studios.


    In this case, we are talking about a very large studio where you can considerably change the acoustics. However, it is still a studio. That is why sound engineers who work there rely on different types of reverberation. I have recently bought a record with the soundtrack for Marcin Krzyształowicz’s movie Pani z przedszkola (Kindergarten Teacher) recorded at the same place. It is a good production and the person responsible for mastering was our old friend and the Grammy award winner, Jacek Gawłowski, but some things still cannot be changed – multi-mono recordings in such space do not sound as if they were recorded at a concert hall. The three-dimensional images of instruments that they offer are not as well-defined and the differentiation is also worse.

    This can also be found on the reviewed album. However, it is helpful that the most important instrument here is the Moog. It is a newly constructed, 55-module instrument characterized by great sound capability, which Craig Leon willingly makes use of. The instruments, mostly the synthesizer, produce very clear sound, next to us. It is fairly warm, dense sound. Although, as it seems, the master tape was a file, the effect is really nice. The quality of pressing is also amazing – the traveling noise is very low and there is almost no crackle. It is worth having this album to see how interestingly electronics can be matched with acoustic instruments. RED Fingerprint.

    Sound quality: 7/10



    - Turntable: AVID HIFI Acutus SP [Custom Version]
    - Cartridges: Miyajima Laboratory KANSUI, review HERE | Miyajima Laboratory SHILABE, review HERE | Miyajima Laboratory ZERO (mono) | Denon DL-103SA, review HERE
    - Phono stage: RCM Audio Sensor Prelude IC, review HERE

    - Compact Disc Player: Ancient Audio AIR V-edition, review HERE
    - Multiformat Player: Cambridge Audio Azur 752BD
    - Line Preamplifier: Polaris III [Custom Version] + AC Regenerator, regular version review (in Polish) HERE
    - Power amplifier: Soulution 710
    - Integrated Amplifier: Leben CS300XS Custom Version, review HERE

    - Stand mount Loudspeakers: Harbeth M40.1 Domestic, review HERE
    - Stands for Harbeths: Acoustic Revive Custom Series Loudspeaker Stands
    - Real-Sound Processor: SPEC RSP-101/GL
    - Integrated Amplifier/Headphone amplifier: Leben CS300XS Custom Version, review HERE
    - Headphones: HIFIMAN HE-6, review HERE | HIFIMAN HE-500, review HERE | HIFIMAN HE-300, review HERE | Sennheiser HD800 | AKG K701, review (in Polish) HERE | Ultrasone PROLine 2500, Beyerdynamic DT-990 Pro, version 600 - reviews (in Polish): HERE, HERE, HERE
    - Headphone Stands: Klutz Design CanCans (x 3), review (in Polish) HERE
    - Headphone Cables: Entreq Konstantin 2010/Sennheiser HD800/HIFIMAN HE-500, review HERE

    - Portable Player: HIFIMAN HM-801
    - USB Cables: Acoustic Revive USB-1.0SP (1 m) | Acoustic Revive USB-5.0PL (5 m), review HERE
    - LAN Cables: Acoustic Revive LAN-1.0 PA (kable ) | RLI-1 (filtry), review HERE
    - Router: Liksys WAG320N
    - NAS: Synology DS410j/8 TB
    System I
    - Interconnects: Acrolink Mexcel 7N-DA6300, review HERE | preamplifier-power amplifier: Acrolink 8N-A2080III Evo, review HERE
    - Loudspeaker Cables: Tara Labs Omega Onyx, review (in Polish) HERE
    System II
    - Interconnects: Acoustic Revive RCA-1.0PA | XLR-1.0PA II
    - Loudspeaker Cables: Acoustic Revive SPC-PA

    System I
    - Power Cables: Acrolink Mexcel 7N-PC9300, all system, review HERE
    - Power Distributor: Acoustic Revive RTP-4eu Ultimate, review HERE
    - Power Line: fuse – power cable Oyaide Tunami Nigo (6m) – wall sockets 3 x Furutech FT-SWS (R)
    System II
    - Power Cables: Harmonix X-DC350M2R Improved-Version, review (in Polish) HERE | Oyaide GPX-R (x 4 ), review HERE
    - Power Distributor: Oyaide MTS-4e, review HERE
    - Stolik: SolidBase IV Custom, read HERE/all system
    - Anti-vibration Platforms: Acoustic Revive RAF-48H, review HERE/digital sources | Pro Audio Bono [Custom Version]/headphone amplifier/integrated amplifier, review HERE | Acoustic Revive RST-38H/loudspeakers under review/stands for loudspeakers under review
    - Anti-vibration Feets: Franc Audio Accessories Ceramic Disc/ CD Player/Ayon Polaris II Power Supply /products under review, review HERE | Finite Elemente CeraPuc/ products under review, review HERE | Audio Replas OPT-30HG-SC/PL HR Quartz, review HERE
    - Anti-vibration accsories: Audio Replas CNS-7000SZ/power cable, review HERE
    - Quartz Isolators: Acoustic Revive RIQ-5010/CP-4

    - FM Radio: Tivoli Audio Model One