Samson Servo 600 2U amplifier
Purchased to replace a trusty old Servo 550 that finally died powering Dynaudio BM15s in the studio. It sounds really good. My only very minor issue is some low level fan noise. It's very quiet, but the 550 was convection cooled so it was completely silent. There doesn't appear to be any non-fan cooled amps on the market any more at this power rating which is a shame. The noise isn't noticeable at moderate volumes or above, only when listening very quietly, but 4* not 5* because its there.
When I originally set it up there appeared to be considerable ground noise, but I realised I had balanced cables coming from an unbalanced output on my mixer. Changing for unbalanced cables silenced the ground hum immediately... my stupidity. This only happened because it has balanced inputs, which is a positive.
I can't comment on reliability, or compare with more expensive models, but I'll be keeping mine. The 550 was used on loads of commercial releases, so I've had no issues with the sound quality from Samson to date.