How do Digital Amps Mfrs. compare in sound?

I doubt very much that in two yrs ,that so much of an improvement has been made in dig. amps that all of a sudden they have improved that much if any and just how much of a improvement was made.2 years ago there was just as much hype as now.

The two that come to mind that offer UCD is Channel Island (D-200) and Kharma (MP150). The Kharma is a little more money then the CI. You can also go to hypex.nl, order the parts and build one yourself. I have a pair of custom UCD700 made to monos. These output 350 wpc into 8 ohms and 700 wpc into 4 ohms. I am now building another pair. My past amps are; Adcom, GAS Ampzilla, Dynaco ST-70 modded, Melos MAT-180 and Karan KA-i180.

Condocondor, I have no direct experience with the Bel Canto S500 stereo. Just looked at:
http://belcantodesign.com/new2008.html
By reading between the lines, it seems that the S500 may lack the input AC current rectification circuit of the Ref 1000 Mk.2 and Ref 500 Mk.2. I can only venture to guess that in the end the S500 may sound slightly less refined than its mono brothers. Yet, without direct experience, my guess has only the negligible value of the electrons you see on the screen to paint it. G.

Guidocorona, very astute mental clarity on your part! You answered my question regarding value point. I wonder if the Bel Canto Mk.2 upgrade carries over to the stereo amps?

I agree completely with one thing that Stanwal said:

"I would have a long listening session with any of them before buying"

That is because switching amps -- which in most cases are analog devices and not digital) -- like any other technologies, have a sound that is much more characteristic to a manufacturer or an individual model than to a 'class'. Thus the sound can range from bright and distorted to exceedingly musical, from extremely extended to limited in bandwidth, from 'dry' to harmonically rich and complex, from quite rough to incredibly subtle.

It is worth pointing out that the HiFi Critic article is almost 2 years old and that at least 2 of the amps reviewed there are obsolete and withdrawn. Furthermore, From a logician's point of view, the negative inductive reasoning used by the author to draw his generalized condamnation is essentially flawed. . . there may be close to 100 switching amps on the market today. . . he examined 3 and declared them to be wanting, then glibly proceeds to condemn the whole lot, based on his spectacularly limited observations. On the other hand his guilty virdict -- had been most likely decided 'a priori'.

If the same reviewer were to examine with a completely open mind current production of leading switching amplifiers such as the newest bel canto Ref 1000 Mk.2, JRDG 312, and latest Spectron monos (just to name the very few I am most familiar with)(, he may discover that the art and science of reproducing music is not the sole prerogative of traditional -- and sometimes nostalgic -- technologies.

Returning to the original question, within the very limited scope of my experience, one of the highest values in amplification -- regardless of class and technology -- may be the very moderately priced current crop of Bel Canto monoblock amps: the Ref 500 Mk.2 and the Ref 1000 Mk.2. As for which variant of underlying chip set may be best. . . it is a question for which there is no particularly valid answer. . . to paraphrase and old cliche. . . "Tubes and chips don't make music. . . designers with tubes and chips make music!"

G.

I am running the latest and top version of Nuforce, the Reference 9 V2SE. It is very wonderful accross the spectrum, particularly the bass and including the highs. The amp is reported to have high bandwidth, low distortion, near zero phase shift, a very high damping factor and a proprietary modulating signal versus Tri Path etc.

That said I can understand the difference of opinion about these amps. Using a tubed pre (Audio Horizons) my initial sound was amazing in the bass and harsh/glassey in the highs on 2/3 of CD's, noticeable at higher volumes in a very live room. I replaced my silver IC with gold and used Hyperion vibration control discs under the amps and voila! the highs are now sweet, extended and yet tame at high volume on about 80% of CD's. So the amps are sensitive to source material, wire, FRI, EMI, and vibration. They are also psychologically challenging. You hear this incredible extended articulate full bass and look down at the puny little things, knowing you paid less than half what would be usual for this good a sound, and it doesn't add up. But it is worth giving these amps a try. The detail, soundstage and musicality can be amazing if some time is spent on set up. Added to that is portability, low energy use, and space savings.

For those of us a step behind in this debate, which products offer the UCD technology?

I prefer UCD technology as well. I have compared it to Melos MAT-180 and a Karan KA-i180 and prefer the UCD based amp. I use mine with a tubed preamp also.

I have a NuForce integrated I purchased used here on the Gon. It definitely had a nasty glare on top. I sent it in to NuForce (xlnt service) for a V2 upgrade - glare is all gone and it is a very sweet unit with great dynamics - and I only use it with digital sources.

The gentleman I bought it from is, among other skills an equipment reviewer. When we were discussin the upgrade (which was the plan going in) he wrote me that "I think the learning curve is still relatively steep on this kind of stuff which means upgrades not to far out from release (a few years at best) have meaning."

As noted, at least in my experience this has turned out to be true.

Look to the technology the amps are based on. ICE, Tripath, UcD, etc. I have used both Tripath and UcD based amps and I think UcD is better. Either amp is better than most mosfet,jfet, solid state amps. They have no "sound". They will, without adding their own sonic signature, amplify what they are fed. They are "neutral", which is what you want an amp to be. I have stated many times a tube pre with a "class D" amp is a great combination. I also believe any SS amp sounds better with a tube pre. I only know, that for me, "Class D" opens up the sound, highly detailed, very wide sound stage and with the tube pre, produces a warm musical experience. I have been in "hi fi" since 1971. The debate over this new technology has been anything but stifled. Just as SS rose against tubes, cd's replaced cassettes which came out against records; chips will overshadow mosfet/jfets. Each camp will have its champions and shrill voices. There will be product for each technology. Most will go with the new technology, some never will.
Excuse me as I listen to some Bach, produced by my system of cd through tube pre to a "Class D" amp. Debating over technology is not what is important, listening to music is. Less chat, more tunes.

HiFiCritic compared the Bel Canto e.One REF1000, the NuForce 8.5 monoblocks and the Channel Island Audio D100LGR in the September/October 2007 issue. This is a magazine that accepts no advertising in order to be able to say what they think. They were not impressed with the performance of any of the amps. They were quite powerful but the actual sound quality was lacking. As they put it," Poor treble seems a feature of Class D amplification." Some other publications have hinted at this; I remember an Absolute Sound review of 2 Class Ds where the reviewer commended on the necessity of using a tube preamp to tame the top end[ I don't have the issue in front of me]. When I posted a reference to this article previously a mighty roar was heard from owners and SELLERS of Class D amps accusing both the Magazine and myself of being in league with entrenched commercial interests. The loudest roarer was a large audio dealer. The magazine takes no advertising and while I myself am an audio dealer I do not sell electronics. You may well see this repeated here; if so, remember that those who try to stifle debate have something to hide. To me the whole thing is reminiscent of the CD debacle where a new technology was rushed to the market before it was developed.The test is not on line but the HIDICRITIC site has excerpts from a paper presented at a professional conference concerning Class D amps. I would have a long listening session with any of them before I bought one.