Funny you should ask as I have owned both Atma M-60 amp (with Vcaps and Caddock resistors) and currently own the Carver Cherry 180 mono blocks (Vcap output coupling caps and Gold Point stepped attenuator instead of the stock volume pot). It is the precursor to 200 watt precursor to the Crimson and uses KT88 tubes. The Carver tube amp is a remarkable tube amp. It drove all of my speakers without ever clipping including the relatively inefficient Raidho D2.1 and D1. Compared to the Atma M-60, the Carver is much more dynamic, has more precise imaging and deeper soundstage, although slightly less wide soundstage than the M-60, which has more diffuse imaging and soundstage. As far as bass dynamics and extension, the Carver is hands down better and can drive almost any speaker out there. The M-60 requires careful speaker matching because of its OTL design and can sound very loose in the bass if you don't mate it with the right speaker. I would say the M-60 has a smoother, albeit more bland midrange. The M-60 has hands down the most extended crystalline smooth high frequencies I have ever heard from any amp, solid or tube. My experience is based on stock tubes for both amps.
One thing I didn't like about the M-60 was its reliability. Within 6 months of ownership (bought brand new), 3 output tubes failed with a dramatic POP sound from the speakers every time a tube blew itself. I didn't like power transformer hum and tube hiss either. The Carvers are essentially dead silent unless you have your ear a foot away from the power transformer in a ultra quiet room. Then you will hear a very low level hum. It's as quiet if not quieter than the solid state amps I own. I never heard any tube hiss from the Carvers.
