flavo, this sale would include the barely power supply as shown. I originally bought the amp from Virtue with the 'audiophile' 30V/130W power supply, but sold the latter when I acquired the battery power supply. Frankly, I don't know what the wattage produced by the amp is with this power supply, but I always found it pretty sturdy. I simply left it on trickle charge, so I can't tell you how long the battery will supply adequate power for the amp to run. This probably reduced the sound quality a bit, but it was very convenient. I'm afraid I don't know anything replacing the battery because I have never had to do that. However, one neat thing about this power supply is that it has a double-headed power supply cable, so it can power the amp plus a second component that can run on 24V. You can find full details of the power supply on the Virtue Audio website, here:
http://store.virtueaudio.com/product-p/virtu-liion-24v5k-2xout.1.htmThe amp requires an external power supply to function. If you don't use this power supply, you would need to buy another power supply from Virtue to power the amp. Seth and Jason at Virtue Audio are terrific to deal with and they can probably answer these questions for you. Things have been fairly quiet there for a while, but they are still an active business.
I hope this helps.