I used a 100AH Odyssey PC2150 deep cycle battery to power my modified Sony SCD-1. They have vanishingly low impedance, which is a function both of their design and high AH capacity. It's good to add a large amount of capacitance between the terminals-- particularly using an array of parallel capacitors. This filters noise and improves transient response, even into low current loads. Keep the battery cables to the inverter thick and short.
12V Deep Cycle battery with Pure Sinewave inverter for tube amp?
Recently I purchased the largest 12v deep cycle battery that I could find. I also purchased a small 500 watt pure sine inverter. After connecting my El34 Single Ended to the inverter, the results were incredible. I was just curious what the community thought about this idea, comparitively to power conditioners and what not.