roxy54 - agree - amps certainly can be "separate but equal" and system matching is a main issue - including the room - in my experience.
In my case, I went up the Krell line in three stages some years ago - KAV 100, 250, and then to the flagship at the time, the FPB600 . The 600 made a big difference, compared to the KAV amps. It performed excellent, provided the conditions were right. I had flagship but heavy-driven Dynaudio Consequence speakers that could have used two 600s, but amp bridging was not possible, so I sold the whole system. Instead I invested in OTL tube amps, the Atma-Sphere MA-1. With the big Krell, I had to turn the volume too far up, to get the best (full class A) performance from the amp. With the OTL amps, the volume can be more moderate, and still catch most of the action. The Krell was more about "pushing" the music, while OTL is best at "pulling" you into the music.
I find that the MA-1s do exactly what I want, reproduce music in a true way, with full tonal colors, ambience, drive and speed, etc. Even if sometimes I miss the push of the Krell, e g in rock music, I don't think the MA-1s lose out on transients, speed and rythm - maybe the contrary, this is faster. An upgrade some years ago (for reasonable cost) helped with speed and bass.
There is something "star-lighted" and clear with OTL sound - at its best - in my experience. I bought the MA-1s without having the possibility to hear them, based on listening to a little OTL headphone amp, Audiotailor Jade. It was David against Goliath. Why did this little amp, in some important respects, perform better, clearer, more musical -. than the flagship Krell and Dynaudio main system?
The MA-1 amps create a huge, deep and well differentated musical landscape. Provided the source is reasonable good - and even a mobile phone mp3 does some of the trick - there is no doubt that the musicians creating the music are brought forth, more than usual, in hifi. Bad-sounding records don’t fare any better here, but the amps are not "analytic", most of recordings, bad and (especially) medium and good, sound better with the MA-1s than the former amps I have used. Beyond the Krell amps mentioned, this list includes a large Yamaha amp, and a 1970s Revox amp, plus various tube and solid state amps on loan.
Easy-driven speakers are a must, for going the OTL and tube amp way. I use Audiokinesis speakers, tuned to the amps. The system "grips" the room in a better way than the Krell / Dynaudio system managed. There, I used a Velodyne DD18 sub, but I could sell it, with the new system.