Wow, thanks guys. The Zana Deux... what a beauty...
Thanks for the great advice. It looks like a separate DAC is the way to go. What DAC's are you both using with your ZD?
For that kind of money, pick up a Zana Deux. It's a real tube amp front to back. Read the owner's thread - you'll notice that it is usually the final step for most owners. Mine has been around for almost three years and I am still in love. It makes a fine preamp for driving speakers, as well.
If you're interested in solid state, go with the flat-out best: the Beta22.
I'd recommend going with a separate DAC.
DAC chipsets change every 12-18 months. If you buy a combined DAC/Amp, resale gets hurt when people don't want to buy the old chipset.
Also, I'm not sold on batteries. A well-filtered power supply is excellent and will last for decades. When it needs a refurb, you just replace the capacitors. Maybe $20-$30 of parts. Batteries degrade and need to be replaced every few years. You might have to drop a few hundred for new ones, assuming that they're available. I'd rather spend $30 every ten years than a few hundred every four or five.