Will this isolation transformer limit power draw?

Sean...Using an audio program instead of 60 Hz for power is obviously an extreme case.

Isn't it true that the diodes of the power supply only conduct during time intervals when the input 60 Hz voltage is greater than the rail voltage. Most of the time the diodes are not conducting, and the amp "coasts" on what is stored in the PS capacitors. When the amp is under no load, the PS capacitors will charge up to the 60 Hz peak voltage, and the diodes will just be delivering very brief pulses to keep them charged. So, if the power supply has pulses for input, why does the exact shape of the original waveform matter?

In the good old days, an outboard "bank" of capacitors was a popular mod...simple and effective. I believe it would do more good than a transformer.

An outboard bank of caps is FAR less effective than capacitors placed as close as possible to the output devices. That is, as far as storage devices go and minimizing sag on the rails.

As far as the 60 Hz voltage vs the rail voltage goes, the 60 Hz voltage will always be higher than the rails in most conventional designs. If one were using only partial rectification and not a bridge, the charging rate would be far more cyclical. As it is, the cycling with the resultant "glitching" that occurs during a typical charge rate has to do with the diodes themselves turning off and on, which produces ringing and distortion. This can be seen in many amps as a 120 Hz and sometimes even a 180 Hz resonance. This is why many designers are switching over to diodes that recover more quickly as they produce less noise.

Other than that, believe me, a good iso transformer will do GOBS more for you than a bank of caps could in terms of the filtering of noise. Having said that, i am a BIG fan of large capacitor reserves within the component itself, especially in power amps. That's why i've purchased BIG electrolytic cans by the box-full. Sean
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sean...60 Hz ac sinewave input power is at zero volts 120 times per second, and below rail voltage most of the time. (That's why we found a square wave power input was better).

Outboard location of some PS capacitance is OK. After all, some designs (usually "High End") put the entire PS on a separate chassis. Also, it is usual to have some small amount of PS capacitance distributed right on the active circuit boards to minimize the effect of inductance between the PS and the circuits.

Shall we now start a bragging contest to see who has the biggest capacitor :-)

Sooo,

is it a valid, non-stupid, non-deluded audiophile smoke-and-mirrors trick to use an isolation transformer (or a balanced transformer, perhaps) to minimize a slight humming or buzzing sound (ie lower the "noise floor") emitting from my speakers with the Bryston?

What would be better, just plug it to the wall and deal with the noise? I've already used the ground lift switch. My interconnects are all properly grounded at the source side, and my receiver did NOT produce even the slightest bit of noise (the Denon 3803)..

What other ideas would work to rectify the problem?

Sounds like the Bryston has a problem.

Does it hum or buzz when input interconnects are disconnected (ie: only the power amp is connected to the speakers)?

Other ideas...Are the source components and the power amp pluged into different outlets, which may be on oposite phases of the 115 V power? Try putting everything on one plug.

Try the interconnects the other ("wrong") way around. Sometimes this is better.

If this is why you are thinking of an isolation transfromer make sure you can take it back for refund when it doesn't work.