Re Biasing a SS Amp?

You don't say what amp this is so it's difficult to know. We also don't know if the outputs of this amp are bipolar or FET. That makes a difference. In a bipolar amp you can adjust the bias slightly higher so the amp stays in class A for a few watts more before switching to class B. Will it make a difference sonically? Doubtful. Will it prematurely age capacitors and other components due to the increased heat generated. Definitely. If you want a class A amp, buy a class A amp.

Over biasing a class AB amp will only produce more heat without any sonic advantage. About 150ma per the sum of all transistors per channel is about the ceiling for optimum performance. Converting to class A would involve redesigning the circuit altogether

In my opinion it will make it worse. It is called overbiasing. There is optimal amount of bias for any class AB amplifier. Increasing bias makes partial operation in class A but is increasing window of increased gain caused by the fact that two, instead of one, transistors are conducting. This double transconductance is called "gm doubling". Measurements of the same amp with different bias points (Douglas Self) show slightly increased distortions above certain optimal bias point. Overbiasing is not as bad as underbiasing but optimal bias is what you want. In addition class A amps sound better because since they don't have to be linearized so heavily negative feedback can be shallower. Class A amplifiers have gain, before feedback is applied, in order of few hundred while class AB amp gains go in thousands. Deeper feedback can produce TIM (transient intermodulation distortion) - basically an overshooting fast transitions, equal to producing odd harmonics in frequency domain. Also, as Hifigeek1 said, it might age prematurely capacitors, since it was designed for different heat dissipation.

Usually, and I do mean usually, not always, an amp designated as class A/B (as with most amps, regardless of class A or A/B) has several stages, each of which has circuitry that is "biased". Every transistor or tube in the circuit path has to be "biased". That out of the way, now, most people talking about "biasing class A or A/B" are talking about the output pre-drivers and output drivers. This is typically the only part of the circuitry that has an adjustable bias circuit. The other circuits that are "biased" have bias circuitry that you cannot easily adjust. In most cases, the circuitry is already set for a bias of which Class A is present. It is typically the output pre-drivers and output drivers that are only class A/B, the rest is class A. So, lets just talk about the output pre-drivers and output drivers. Yes, you can adjust the bias towards pure class A, and yes, you will hear an audible difference in most cases and yes, it will sound better. I have done this so many times, I have lost count. Most manufacturers that design and construct for class A/B on the output stages do so because of cost. Heat sinks are stupidly expensive. Please see Nelson's pass write-up on Class A and heat sinking on Pass Lab's web page, it is wonderfully written. Also, the transformers and power supply circuitry is not designed for full class A operation. If you read Nelson pass' write up, (there are others, but his is really well done), you need a power supply that is designed and built to handle Class A full, full output operation. This means even more expensive and huge power supply/regulator transformers, power supply capacitors, retification circuitry, etc. All of this (power supply, heat sinking and possibly changing out (not always) the pre-driver and output driver transistors) are the major expense in amplifier costs. This is why they are biased as "class A to a certain output level and then Class A/B afterwards" I have upgraded amps whereby I have changed the tranformers, power supply caps, rectification circuity, heat sinking (Threshold style heatsinks), pre-driver and output driver transistors, etc.) and biased it towards pure full on class A operation. much less efficient because it is biased "on" not only all the time (so is class A/B by-the-way), but it is biased on at full capacity or close to it. There are many amps that you can do this for. But, it is really expensive, which is why the manufacturer didn't do this in the first place.

enjoy