Has anyone used a full-system battery power supply?

Perfect: defense industry contractors make the best. Used in submarines & the like. As you note, you plug them in & the equip in them. The amperage is not always very high, though. The ones I've seen are HUGE, ugly, best left hidden somewhere...

In Europe they come reasonably cheap: ~$1k for a 12amp that can last 3-4 hrs unplugged. Maintenance every 2-3 yrs.

Never tried one -- maybe I should.

They make battery systems for this purpose. The can be plugged into the wall and charged and last several hours. I saw one once at my local hi fi dealer but I have no idea who made it

It would be possiable to put an amp on batteries. An 100 watt SS amp typically has a power supply of around 60 volts plus and minus. If you put 5 car batteries in series for the +60 and another 5 for the -60 power supply rails, the amp would play for several hours before needing the batteries recharged. The charging system is no easy task for that many batteries in series but for testing purposes just start out with fresh batteries. I think it would produce killer sound and would be easy to hook up on most SS amps. The 300+ volts on most tube amps would require even more batteries and would likely be unfeasiable. Chris

I use a Rowland amp with battery and a Levinson preamp that regenerates the AC. I'm adding an Exact Power any day now plus I also use an input transformer between preamp and CD player. Sound is great as is, we'll see what happens when I put the EP in. I once used a TrippLite UPS with pure sine wave output and after taking it out, felt that the system opened up again. Plus the computer device while hefty buzzed and I'm convinced it put more hash into the line. Try an input transformer, you might be surprised. It kills noise coming from interchassis leakage. I found the bass to improve and the noise floor to drop noticeably. I like Q-Audio but you can also try Jensen IsoMax from Markertek. For a bit over 100 bucks it may be the best tweak most people are afraid to try (as in input transformers are bad for some reason). I don't think a battery to power a whole system is feasible but maybe you can get a generator and then filter it. Make your own dedicated line. Home Depot has all sorts of models for $200-1000. The smell of gas and the lawn mower noise may drown out your system, though.