When stereo equipment is concerned, the ultimate goal for AC wall power is to convert it to DC. Battery voltage. So, why not start with batteries in the first place? It’s a question we’re often asked.
A handful of manufacturers of smaller source and control gear have relied upon battery power for years. A few innovators even manufacture separate DC battery power packs for headphone amplifiers and a braver few, like KingRex, a lead acid beast that can work with small power amplifiers.
Aside from the obvious limitations of operational life, charging requirements, chemicals, and decreasing performance over time, batteries do have advantages like low noise. Where AC/DC power supplies go to great lengths to make clean DC, batteries are all over this like white on rice.
PS Audio has only gone the battery route once. Our first prototype of the original phono preamplifier, circa 1974, ran on a pair of 9v batteries. Very convenient, but as soon as they were replaced with a legit AC/DC supply, sound quality immediately improved.
The good news for most of us is that AC/DC power supply and capacitor technology have gotten only better over the decades. Today, we can build DC supplies with noise levels rivaling those of batteries.
Still. Batteries are cool.