Gyphon makes several amps that operate pure class A and consequently are very big, very hot , have huge power supplies, and only put 150-175 watts into 8ohm loads due to inherent class A inefficiency. Their power supplies do allow them to double down into difficult loads ( 300w 4ohms, 600w 2ohms ). There is a switch which allows for AB bias operation for "non critical" listening which saves electricity and heat. I never use it. I always run class A. Maich, the reason pure class A operation is rare in ss amps (even with a switch for AB)is for the above reasons and the expense of the power supplies, required capacitance, and heat sinks. It's nearly impossible to build one thats operates in pure class A with significant output that's less than 200 lbs or so and they get very very hot and use lots and lots of electricity. 95% of the market would rule them out on these grounds alone not to mention the $/watt ratio they represent to less picky consumers. Most people would not justify the sonic benefits they(class A) confer.IMHO they are great for difficult loads (4 ohm and under) or for high efficiency speakers. I personaly am hooked on these big ugly beasts. - Jim
