I've done some quick power usage measurements for you.

And thank you very much. This is exactly the information I was looking for.

I have acquired a 5 Amp-hour 12-volt gel-cell battery (probably used for emergency lighting system, maybe an alarm system?) for $25. This should give me about 6 hours of listening time, except that I won't want to deep-cycle this battery (lead-acid) so I'll re-charge it daily. Hopefully this weekend I'll have it all together.

Thanks again for the information.

tanstaafl.

"There Ain't No Such Thing As A Free Lunch"