I recently had an opportunity to audition a pair of Bel Canto Ref600 monos for a week, followed by four days with a new Bryston 4b3 on my Thiel 2.4s. My preamp is an Aesthetix Janus. I also had the Red Dragon Audio Class D stuff, both a pair of the 500M monos based on an IcePower board and the 500S based on a Pascal board. I had to rule out the Red Dragon stuff because on my system they sounded for lack of a better word "digital." The decay on notes seemed unusually long and unnatural with both the Red Dragon options and the stereo amp based on the Pascal board which is supposed to have some special engineering in it unique to Pascal sounded considerably brighter than the Icepower based monos. The Red Dragon amps (both flavors) WERE very dynamic, a little threadbare in the midrange and while they weren't bad, especially for the money, I wouldn't be able to live with them so back they went. I wanted to try some Class D stuff because I actually had pretty good experience with some of the earlier Bel Canto Products, that is the 300M and the 300S amps. Those amplifiers did alot "right" at low and moderate volumes but at high volumes they seemed to struggle and compress a bit. Not a good permanent match. That's why I had HIGH hopes for the new Bel Canto Ref 600s. Those hopes were quickly dashed by my finding that in my system the Ref 600s, while having a unique immediacy to the sound and being very dynamic and having a very fleshed out nice midrange and lower midrange and bass, seemed to be fairly significantly recessed throughout the upper midrange and I blame that tonal anomaly for the lack of "air" in the presentation. Very dynamic, imaged exceedingly well but no cigar on the Ref600s. I couldn't live with them. Then the Bryston went in for four days and it was a breath of fresh air. Extremely neutral, beautiful delicate highs, very good (but not great) imaging, great bass both taut and tuneful, never ran out of gas even when driving the speakers louder than I'd normally. The only thing about the Bryston is that at high volumes I found listening to them a little fatiguing. They seem (to me) to be great studio or lab appliances and if you want total utter neutrality the Bryston may be your best bet. I will also say I heard the Bryston squared series many years ago and thought they were hard and brittle. With the new cubed series that problem is largely gone and the highs are beautifully rendered, cymbals shimmer and everything has the right timbre without being overly etched. But its definitely in no way a "romantic" view into the music. Listening to orchestral music the Bryston was mid to mid-rear in the hall, there was no forward midrange that in other amps something shifts the perspective a little closer to the stage. So The Bryston is still in the running, and I'm looking to try one of the XA series Pass products but I'm still deciding on which one(s) to go with for the trial. I'll report back on my findings. I hope this is at least somewhat helpful. Its difficult to adequately describe (for me anyway) in words the differences between the amplifiers but I'll continue to try.
