When comparing solid state or tube amps, be aware that the rated output is based on impedance. Speakers vary greatly in both impedance and efficiency, making this a difficult decision to make if looking at specifications without every fact revealed.
What follows is a perfect example of how output power ratings can be confusing to the buyer after auditioning and not getting the results they expected.
Compare a large solid state amp rated at 1000 watts compared to a 200 watt Atma-Sphere OTL. For the speaker, an early (1990) pair of A-1 Sound-Lab.
The 1000 watt solid state amp drops to about 75 watts at the most difficult to drive bass frequencies (80 HZ and below) as the impedance rises to 56 ohms (+). The Atma-Sphere MA-2 OTL will produce more than 200 watts into that same difficult load.
The Atma-Sphere will have problems with that same speaker at 22K because the load is now 2 Ohms, but since there is so little music at 22K it becomes irrelevant. The outcome is the 1000 watt amp is clipping much of the time and the Atma-Sphere will drive the paint off the wall.
The listener is confused, why more volume with 200 watts than 1000? The problem begins with most speakers impedance being listed as "nominal." The actual full bandwidth impedance is seldom revealed.
Some speaker designs are extremely low impedance (below 2 ohms) and other vary at different points in the frequency spectrum. Yet another reason to choose an amp design that's sound appeals (transistor or tube) and try it in YOUR system with YOUR speakers to see if the combo flies.
