Krell KSA 50 vs. todays ss amps?

My recollection is that the Mk II had some changes made to it to make it more stable--I think if you shot an e-mail or made a call to Krell they could probably tell you pretty quickly.

Not sure if you're talking about the original KSA50 (and 50Mk II, which I owned for a while) or the 50S, which Dave sent the links about. I must say the old KSA 50 was a very nice amp, quite sweet sounding for a solid state design, with far more power, bass control and clarity than any solid state amp I was hearing at the time. If I still owned it today I might recognize that today's designs, at the top end, might have better quality parts available to them now (higher speed diodes, maybe some better power supply regulation, etc.) that might make them objectively better, but I'd probably still be happy with the sound of the Krell. Going purely from my memory, I don't think it has the refinement of the best solid state designs available today, but it is a well-engineered design that has a lot of strong points. John Atkinson a few years back did a comparison of a Krell KSA 50 Mk II (he always seemed to like that amp) against a new Krell design, likely one of the FPB series, in Stereophile; his comments at the time were interesting, and did not find the KSA hopelessly outdated, if I recall correctly. Worth tracking down, if you can find it.

I traded in my KSA 50 for an 80; the 80 indeed did have more power, was more refined (once it warmed up) though not quite as sweet in the highs, had better bass quality and control, and generally was a better amp. Big problem with the KSA 50 was that it used a cooling fan, which could eventually wear out, vs. the 80's massive heat sinks. Both of these amps could heat a good sized room, as they ran in Class A all the time. Neither of these amps can give you the midrange of a great tube amp, but both of them excel at delivering power into demanding loads, which is what their design goal at the time was (no coincidence that Krell was often demoing with Apogee speakers).