Does just adding additional capacitors (higher overall capacitance) improve the performance of an amplifier, if everything else is held the same? In other words, if you would take a 4B-SST/2, leaving everything the same but doubling the capacitance by just adding twice as many of the same capacitors, would there be any nominal increase in performance?
First off, you have to understand what all that capacitance is for, what it does. You plug your amp into an AC wall outlet which supplies power for your amplifier, but it has to be converted into DC first. That is accomplished by the amplifiers power supply. With linear supplies, a step down transformer lowers the AC voltage which is then rectified into DC, but not very smooth DC. A large bank of filter capacitors then smooths the ripple.
How much percentage of ripple are you willing to accept? Well, it kind of depends on how much capacitance you are willing to devote to the power supply. At some point you get diminishing returns and adding additional capacitance doesn't gain you anything.
Power supply regulation is as important, necessary for good amplifier performance too. Some amplifiers employ elaborate filters and regulation, but it all adds up in size, cost.
If your power supply sags and surges, cannot supply enough smoothing, then add more capacitance. You have to test bench the amplifier under dynamic (real world) conditions.
Personally I think a good hunk of transformer is more important than a massive bank of filter capacitors.
