QThis amp has a huge fault: after thirty hours of run-in time, it sounds so nice you think it's at its best. By the way, its horrendously long settling- and run-in time is made of long plateaus, where apparently there's no improvement. I'd say the run-in time is no less than 200 hours; maybe - maybe - even more, as it seems to me it's still improving after 400 hours and more. Yes, because this is my new amp, I liked it so much I just had to buy the review sample. If you're only interested in knowing if I liked it or not, the review is over, for you.

But maybe you would like to know something more, as this power amp is so outstanding in its sound quality to represent a small revolution in the price/performance ratio in the weird world of sound reproduction.

A brief technical description

GamuT is a Danish company, 20 years old, but, until four or five years ago, it was known mainly in the North-European market, under the SiriuS name, manufacturing amps for the pro and audiophile market. During the last four or five years GamuT has gained resonance outside its original market, thanks to a number of enthusiastic reviews about their amps. The D200 core is its power stage, which uses only 2 MOSFET devices, one for the positive and one for the negative half of the circuit (it is a symmetrical amp) and it is able to draw 200W out of them. Rumours are that these devices weren't designed for audio purposes; the way in which they are employed and the operating points are this amp's real secret. An entire range of brothers takes advantage of these same devices (or derivatives thereof), the S100, the D100, the M200 and the M250, and the cost-no-object S300 and S600M (you might need structural modifications to your sound room in order to be able to install these two). They are complemented, in the GamuT range, by the C2R preamp and the CD1 CD player. As for the rest of the design, as I was saying, this is a fully symmetrical amp, with an intrinsically symmetrical input stage, providing the ability to use both single ended and balanced sources (you just have to use shorting plugs, included in the package, should you have a single ended preamp). The number of amplification stages is 5 or 7, according to its designer, "depends on how you want to count them". The amp uses negative feedback; the designer's take on negative feedback is that it's one of the fundamental mechanisms of every working thing, and that it can be bad only if it is badly applied. It's a class AB, high bias amp.

Why is the choice of a two-devices only power stage so interesting and so important? In the history of high fidelity, it was often observed that, in a family of amplifiers, the smallest was the better sounding; one of the possible explanations of that is the fact that, in a small amp, there are fewer devices, which reduces (or eliminates) the chance, in real life (dynamic) working conditions, of matching problems or of thermal dispersion of the characteristics. Ole Lund Christensen (let's give a name to the designer) has a more down-to-earth explanation also: these amps were designed for professional use too; the less devices you have, the less are prone to go AWOL; it's simpler to track a failure if you have less components. This is not to say that GamuT amps are prone to failure; they are in use in recording studios (an outstanding example can be seen at http://www.ampspeaker.com) where they have been on since twenty years without a glitch. Don't consider this an invitation to leave the amps perpetually on, as, according to the designer, the amp performs at its best after an hour (I would add another 30 minutes, at least, but that's my reviewer's attitude). During my life with the amp. I haven't experienced any problem, and, as you might know, we have had the hottest, dampest summer of the last century.

The power switch is on the front panel; on the back panel, there are an IEC mains socket, RCA and XLR input sockets and two pairs of binding posts (high quality WBT ones, respecting the IEC nannyish rules), one devised as "normal", the other +one as "direct", the difference being the lack of a Zobel network on this latter, which, according to the designer, grants better sound quality on the high range, provided you don't connect strongly capacitive loads (for measurements and electrostatic loudspeakers, the use of the "normal" output is compulsory) or speakers using attenuation networks on their tweeter crossover (in which case, the lack of a Zobel network is pointless). The amp is rated at 200W on a 8 ohm load, doubling its output on a 4 ohm load and continuing to improve until 1.5 ohm; a load lower than 1.5 ohm triggers the protection circuit. To explain this choice, the designer tells us that he had to draw a line between a load and a short somewhere, and that he chose 1.5 ohm as very few currently available speakers go below that load; if your preferred speakers are among the few, you can order a custom configured amp, able to cope with lower impedances. To testify the professional heritage of the amp, many protection schemes are implemented which make this amp almost bomb-proof electrically; after switching the amp on, a relais for each channel sets the output stage ready after the working conditions have been deemed safe by the protection circuits; the relais disengage the output some moments after the amp has been powered off. The aspect of the amp, very matter of fact except for the small bronze plate bearing the manufacturer's logo and the amp's model, suggests this professional heritage also; the amp is available in black or in silver, with or without front handles. All of the D/M series amps share the same chassis, allowing for field (or at least, fast) upgrades; the modular design allows for easy servicing and updates, should they become available. The amp's gain is controlled by a couple of dip-switches per channel (the amp is completely dual mono, from its toroid transformers to its output devices) and there are four available gain steps - you need your dealer's help to change that setting. Mine is set up for minimum gain; I wouldn't swear it or accept a blind test, but I think it sounds better this way - if the gain structure of your system can cope with that,I mean, if your preamp is a high-gain device and/or your listening habits allow for it (in my opinion, optimal listening levels should be with the preamp potentiometer set to 12 o'clock, not to 9 o'clock, as most people seem to prefer), I think you should have it set up this way.

Sound quality (qualities?)

I was complaining about the eternal run-in time, above; as I was telling you, I almost sent the amp back to the distributor, after the standard lent time, evaluating it as a very good amp, almost outstanding for its price range, with many exceptional qualities and some apparent drawbacks, sturdy and reliable, but not a reference level amp - a champion in its price range, maybe, but not redefining the concept of what an amp at not-insane prices can do as it was reported to be (the GamuT D200 must be one of the most respected amps of these years in the audiophile press circle). I experienced a speed, an ability to track the music signal, an immediacy which I was used to find in much lower powered amps, normally equipped with lightbulbs, coupled with a neutrality and an ability to control the lower bass which are out of the reach of those same tube amps; but at the same time, it was almost as if the harmonics couldn't fully develop, as if they were impeded. The other problem I detected was a certain graininess, a lack of ease in the high range. The soundstaging and imaging abilities were - and that should have been enough to warn me about what was to come later - exceptional, acoustic spaces were delineated with such a precision that I should have spotted out this amp's excellent resolution immediately.

I even called the distributor to arrange for sending the amp back; he asked me how much run-in time I gave to the amp; I told him and he suggested me to keep the amp a little bit longer, as a change was soon to come.
I used the amp as my everyday workhorse for some weeks, just listening to music in a relaxed way before re-evaluating its performance critically.
When the evaluation days came, something had changed. Big time.
The amp didn't lose its original virtues, most notably its extraordinary immediacy, its uncanny ability to track the music signal. This feature is difficult to explain if you haven't experienced it by yourself; it is as if someone had thrown away a host of electronic components in the signal path, as if the signal were able to run unimpeded. It's an immediate perception, which is difficult to rationalize, so it's hard to explain.

The other feature which hit me is the amp's neutrality, from the direct output in particular. The normal output is a smidge darker than the direct one; it is entirely possible that, in a brighter system than mine, the normal output might be preferred - but I noticed a slightly superior ability to resolve detail using the direct output. Neutrality as in lack of coloration; the D200 sound is as near to the zero grade of coloration as I have heard - the Krell FPB200 is a little bit dark and is provided of a notoriously larger than life mid-bass. This provides the amp from the U.S. the kind of authority and foundation which the GamuT seems to lack at first, and which can make this latter, in comparison, seem a little bit limited in low bass performance, but you soon realize that the Krell is slower and less able to track the signal as a result.

By the way, a byproduct of this signal-tracking abilty is the GamuT's attitude to follow the rhythm (yes, that famous PRAT - Pace, Rhythm and Timing - thing). This amp pulls a disappearing act and gives way to the rhythmical qualities of the original performance. I know, to some people the concept of rhythm in an amp is considered a non-issue - don't you tap your feet even listening to a transistor radio? Maybe they're right, but I have heard positively narcoleptic systems, which were able to bore even the most motivated listener; as another (Danish, by chance) manufacturer tagline goes, "life is too short for boring hi-fi". Maybe the PRAT naysayers have a point when they say that the quality is gained at the expense of subjective bandwidth extension; the GamuT is the proof that this is not the only way to design a PRAT friendly amp, as its high frequency extension is seemingly limitless (I told earlier you about the bass).

The original recording venue reconstruction is sensational, in focus, extension and delimitation. I usually take focus for granted, with correctly designed devices and decent system set-up; extension is, in most cases, limited by a constrained loudspeaker positioning, but I'd swear that the GamuT amp, as I experienced trying improbable speakers positions (no, I wasn't trying to see if the GamuT could cope with that, only double-checking the CARA software, which I might write a full review of in the future), is able to improve this parameter even in rooms unsuited for a correct placement. I think I can say it: I think a staging of this kind is standard-setting; furthermore, you aren't forced to use speakers which introduce their own aberrations. As for delimitation: how many times have you experienced systems imposing their own (enormous at times, but their own anyway) dimensions to the soundstage? The GamuT disappears, again, at least judging by the many different venues it brought to my room.

The lack of fluidity on the high range is gone; the slight harmonics development difficulty, by comparison with my previous reference, has been there for a while, but I'd say that it's gone too, by now. I realise I haven't written about the GamuT's dynamic abilities, but I think, if you have read above, you can guess something. It's in the dynamic performance that the GamuT takes advantage from that immediacy I have been writing about (all the time); you get an incredible feeling of freedom, both in the macro- and in the micro-domain, which makes for a credible, realistic (not unduly emphasized) dynamic performance.

I know that somebody is telling around that the D200, above a certain volume level, isn't able to deliver what it can deliver anymore. I don't know: my different speakers, while being inefficient by today's standards, are (all of them) quite easy to drive; I have tried to raise the volume much above my usual listening levels, without any negative effect; I will keep you updated when I will be able to try harder to drive speakers. I shall add that the observations on this fault, as those I read on a slight graininess, which I can't feel anymore, were about the previous versions of the D200, as this one is the Mk3 iteration, which sports a new input circuit derived from Ole Lund Christensen's statement amps.

To sum up…

Is this the perfect amp? No, even if it is, overall, the best one I've ever had in my house. Maybe it's possible to do better in the field of instrumental colour, as single ended tube amps, in my experience, do; it's possible that some other listeners prefer a more authoritative presentation. Me, I think that, among the amps which don't sport fantasy prices, this one is the best compromise - in my system it replaced an amp which, while being long out of production, sported a price which was at least 50% higher (double the price, down here in Italy).
Anybody looking for a top level amp and not taking the chance to listen to this one (or to its bigger mates M200 and M250) is wasting the chance to save (or to better invest) a remarkable amount of money.
I'd be curious to verify how much better the six-time higher price GamuT S300 is…