I am a firm believer in over-specified power supplies in audio, for several reasons:
Large transformers tend to have high primary inductance, this acts as a RF filter, no garbage in, no garbage out.
An over-specified transformer will not distort or limit its voltage going to the PS caps, due to the HUGE current spikes generated by the rectifiers (more than 10 times the average current).
Large capacitors generally have low ESR (equivalent series resistance). PS caps are effectively in series with the output signal, the less ESR the more transparent and "fast" the sound quality. This seems couter-intuitive because conventionally circuit diagrams are drawn with caps in paralell to ground and transistors or tubes in series with the output, however, if we mentally re-draw the circuit, it makes sense.
There are three main "loops" in a typical amplifier circuit:
1- The power transformer secondary + rectifiers form an AC loop that gets rectified and feeds>
2- The PS capacitors, which feeds DC to the control devices (tubes or transistors), which modulate the PS with an AC fac-simile of the input signal (music is variable-frequency/intensity AC), which generates>
3 - The output AC loop, formed by electrons flowing from PS ground to the PS capacitor (+) terminal, then through the tubes and transistors, then to the output. The output AC loop is closed through the load (speakers or the next component input impedance.
In other words:
A preamp or power amp uses tubes or transistors to AC-modulate (to the tune of the music) voltage coming from a power supply, which is the source of all power delivered to the load.
Transistors or tubes act as "control valves", allowing more or less of the PS voltage to pass to the output, hence the term "valve" adopted in the UK for tubes. Also, a FET's control element is called gate for the same reason.
A good listen to any Naim CD player with the Super Cap optional power supplies will convert the non-believer. Or a Musical Fidelity heaphone amp with the high-current PS.
Another example: ARC preamplifier's power supplies are over-specified by at least a factor of ten. ARC's tube preamps are known to sound as good or better than many transistor preamps in the bass.
P.S. I am not associated with Naim, MF or ARC...but I used to own an ASR Emmitter II amp with 1,000,000 uF (yes, one Farad) in the double-mono power supplies. Its bass quality, soundstaging and dead-quiet background are unsurpassed in my experience.
