There are three principal ways to power an amplifier:
1 a simple unregulated power supply consisting of transformer, rectifiers, and reservoir capacitors;
2 a linear regulated power supply;
3 a switch-mode power supply.
It is immediately obvious that the first and simplest option will be the most cost-effective, but at a first glance it seems likely to compromise noise and ripple performance, and possibly interchannel crosstalk. It is therefore worthwhile to examine the pros and cons of each technology in a little more detail.
Simple, reliable, ...