nanofarad

Batterys should be perfect power for individual audio components. They can be placed very close to where they are needed, share a ground only with themselves and the circuit they power, and are already DC. No rectification required. Trouble is they usually don't sound as good as well designed switching/linear power supply's. Much of this is because current leaving a battery substrate (like the plates immersed in acid on SLA's) does not do so in an orderly fashion. Additional circuitry is needed to stiffen this current so it can respond to the instant transients that are what music , for example, are all about. Different batterys have different "sounds" to them also, which opens another layer of hell to deal with. Not saying they don't have there place, they do. I only have experience powering small circuits, but can imagine the same problems would remain on a larger scale. Having said all that a whole house system, solar or wind, that is battery stored DC inverted to AC? If so that would be way above average quality if the proper equipment was spec'd. Way better than the 2 very bad AC power scenarios Daphne described at least. Very glad to have consistent voltage where I live.

Speaking only about the music there is no doubt AC plays a huge part on sound quality. I remember years ago reading about very expensive power cables/ ends/receptacles and laughing. No longer. I don't have a budget for the high dollar isolators, filter regenerators and the like, but most have the budget for dedicated lines, quality outlets, and a couple of well placed isolation transformers. That alone can be a bigger improvement than a dac or sound card change, for example. I went to balanced power 2 yrs ago and have never looked back. Nobody in this hobby can truly evaluate the sound of their system without being reasonably confident they have done (to the best of their budget) a good AC audit starting at the breaker box. There is a phenomenal amount of physics involved with AC transmission leaving us mere mortals best suited to keeping a sharp eye on the subject and experimenting with what sounds like it might be reasonable or necessary for our particular systems. Also Daphne, agreed, the snake oil................