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RCM Audio theRIAA phono stage review by HiFi+

"...it’s actually the kind of product that defines the best of high-end audio, a phono stage that just replays vinyl masterfully. No fuss, no frills, no fancy-schmancy casework..."

RCM Audio might not be the first name you reach for when it comes to up-scale phono stages. The company is a small six-man affair out of Katowice, in Poland. When not making phono stages, RCM’s other job is a Polish high-end importer with brands like SME and Dynavector in its arsenal, so perhaps its resolutely turntable-related product line (just three products, two of which are phono stages alongside an integrated valve amplifier) makes sense.

RCM Audio’s best-known product up to this time was the Sensor Prelude IC, a two box IC based MM/MC phono stage with passive RIAA equalisation, in two drab boxes. This sub-£2,000 phono preamp is the kind of giant killer that many have compared favourably to practically every phono stage irrespective of price, and has a habit of turning reviewers into owners in minutes. It was so good in fact that it was hard to see how to better it, unless you are in the habit of referencing things by their size and thickness of front panel. The nearest thing to criticism of the RCM (prosaic nature of the cases aside) was that it had relatively limited cartridge loading options, especially compared to top-flight stages from Pass and Burmester.

This created something of a conundrum for RCM Audio. The Sensor Prelude IC was almost too cheap for today’s high-end buyers, but getting significantly better performance from what is one of today’s best phono stages was proving difficult. However, learning from the Sensor Prelude IC allowed the company to come up with THERIAA. In fact, the THERIAA could be summed up as a dual mono, high-specification version of the Sensor, but without the small value decoupling capacitors dotted around the circuit.

It is still a two box IC-based MM/MC phono stage with passive RIAA equalisation, in two boxes, albeit ‘drab’ is replaced with ‘well-built, but functional’. But the sophistication of the adjustable gain and loading (this time using expensive Omron DIP switches) and an expensive laundry list of highspec components from Elna, Nichicon, Vishay and more has helped bring the linearity to the RIAA curve from an already deeply impressive ±0.3dB to a remarkable ±0.1dB across the 20Hz-20kHz range.

That ‘well-built, but functional case’ – made by Fischer Elektronic of Germany – is not just for show. The case is made from anodised aluminium with custom damping plate and the 10mm thick aluminium partitions that entirely separate the two channels help to minimise any potential environmental noise pollution, which can be a problem specific to trying to eek out the maximum performance out of a cartridge. It will never appeal to those who are looking for highly polished front panels and delicate curves milled into an inches-thick panel, but if you value the sound of your LPs rather than the look of your replay system, this is for you.

RCM Audio recommends using the phono stage in balanced mode throughout if possible (this isn’t as odd as it sounds, the output from a cartridge runs in balanced operation) and it makes a difference. I used it with an SME Model 10 and principally with the Benz SLR cartridge as a front end, into a number of amplifier and speaker combinations to see if the ‘wow’ I got when using it into something illustrious also applied when using it with things a bit more down to earth. It might be odd using a phono stage that costs four and a bit times as much as the Sugden A21se it was connected to, but the ‘wow’ factor shone through nevertheless.

It’s principle ‘wow’ factor likes in its absolute honesty. The kind of honesty you realise you don’t hear that often from phono stages until you hear something like THERIAA. Here’s how it works; you put on one record, shake your head in disbelief because you must be hearing things, then put on the next and realise, no, it wasn’t some kind of hallucination. It really is that good. I put it up against the lovely sounding Pass Labs two boxer we use as the studio reference phono stage (which just happens to be a close price match and just as flexible in cartridge loading). The Pass is a fixture because it combines excellent detail resolution with an ability to prevent the poor sound of some vinyl recordings from undermining the enjoyment of the album. It does this by sounding a touch ‘warm’. But THERIAA does the same, and does it by sounding absolutely honest. I’ve got a dodgy Spanish import of Dylan’s Blood On The Tracks that I use for this kind of torture, because it sounds like it came off the 1,500th generation 8-track master and was pressed on ‘oil crisis’ vinyl that is almost see through. Most make it sound thin and weedy, because it is, and an unloved version of a beloved classic album of pain and divorce. The Pass works because it warms up the sound, but THERIAA works to bring out that thin and weedy sound and still make it sound like Dylan’s arguably finest hour. It doesn’t mask it, warm it up or present it as something other than it is, and in the process makes a sound more insightful than many stages.

Naturally, this also makes THERIAA extremely good at determining the difference in vinyl quality. I have a good version of Fleetwood Mac’s Rumours and an outstanding version on two 45rpm thick slabs of near-silent vinyl. Not only does THERIAA let you know which one is which with unquestioning accuracy, but lets you ‘in’ on the music in both.

I realised quickly with THERIAA that the words are all about the quality of everything else in the chain apart from the phono stage. That’s because it’s one of those rare pieces of equipment that doesn’t impose itself on the signal chain. These are rare in the extreme in phono stages. Here, there is an absence of character, letting you hear either what your phono cartridge is doing, or – better yet – precisely what is happening in those grooves. In a way, what this reminds me of in the world of phono stages is the Burmester 100, which borders of being an archival-grade phono stage for transcribing albums in a forensic manner. In some ways, THERIAA has the edge over the Burmester, because there is the merest sense of additional richness to the Model 100 that THERIAA doesn’t have. And yet, for all that, it’s never stark or etched. It’s just… the sound of vinyl.

I know there will be those who object to the concept of a high-priced phono stage that doesn’t include a range of EQ curves, but this delivers such a powerful and honest performance on RIAA, I don’t really care. If I had a lot of records cut in the ‘red zone’ (pre-RIAA mono recordings and some of those more controversial late 1950s/early 1960s stereo pressings that may or may not be following the RIAA curve) I might be more upset, but I’d be more upset that I couldn’t get THERIAA performance on more than RIAA. However, the name is a bit of a giveaway – but I guess THERIAACOLUMBIATELDECEMIDECCA is a bit of a mouthful.

Otherwise the sole criticism I can think of is now one of excess, but excess in the right way. This is a demanding phono stage; not in a fussy, ‘make a mistake and I’ll tell your friends’ kind of way, but more in a ‘if you don’t have a deck and cartridge of the best quality, you’ll think this is just another phono stage’ manner. It will always sound extremely good, but the ‘remarkable’ part that will have you up all night playing records only happens when everything is in place. This means some with good phono front ends will likely compare something like the Sensor Prelude IC with THERIAA and conclude there’s not much of a difference to justify the price hike. Those with a front-end worthy of being in such vaulted company will have no such qualms and hear a monumental difference between THERIAA and mere mortal phono stages.

The thing about RCM Audio’s THERIAA is it could pass unnoticed next to the big guns. But it’s actually the kind of product that defines the best of high-end audio, a phono stage that just replays vinyl masterfully. No fuss, no frills, no fancy-schmancy casework, no big budget marketing campaign or slick salespeople telling you how wonderful it is. You just plug it in, and know how good it is, if your vinyl chain is up to the challenge. If you take your vinyl seriously, be thankful things like THERIAA exist, because they show there’s more to high-end audio than meets the eye. +

Reproduced from HI-FI+ Issue 102 (PDF).