@rutter, at ~$1000, you can look into the new Woo Audio WA11 Dac/Amp that will give you 1.2 Watt with 4.4 out. I personally think the 1A/1Z with balance out and high gain is sufficient to drive the Z1r
I had plenty of volume room with the ZX300 on high gain balanced but the sound I'd argue clearly wasn't right whereas the $100 Fiio A5 I think ends up sounding better single-ended you'd think because of 800mw into 32 ohms. I can't find the Sony power specifications after a quick search but the ZX300 and WM1A are supposed to be within 50mw of one another at like 250mw (into what?). So what is the wm1a supposed to do over the ZX300 to drive these? Not to mention people are claiming balanced the two sound very close to one another. The ZX300 sounds like the wm1a, which sounds like the wm1z, and the DX2xxs with amp 8 some say sound better than the wm1z... you gotta love this forum.
Astell & Kern KANN is right on $1K these days.
Looks questionable.