I bought a Google Nexus 7 (currently on 4.3) when they came out. It's a nice enough device (in many ways, however the limits on gain make it all but unusable without external powered speakers or amplified headphones for older, un-squashed audio as in old movies... understood there are 'booster' apps that will allow a boost from within the digital domain, but last time I checked, they all seemed kind of dicey).
With regard to potential sound quality upgrade from moving to a prosumer outboard DAC -- absolutely. I can't answer for every device, but consumer devices tend to have pretty lame conversion. All DAC chips are not made the same and analog circuitry 'outside' the digital path is typically a BIG quality bottleneck in these devices. When I tested my motherboard interface, my laptop, my phone, and my tablet against my external 'pro' converter (MOTU 828mkII, made for music production; a respectable but not universally loved unit), the sonic difference was quite striking over the same playback rig (Event 20/20bas speakers, flat +/- 2 dB 38-20kHz).
Given a good player (don't start me) or a good streaming interface (I use MOG which has many good things -- and all 320 kbps quality -- but could stand a few improvements, which it will supposedly get when it becomes Beats Music any day now) and a good amp/speaker rig, a tablet could be a great little media device. IF it had good conversion instead of tinky, mid-fi consumer sound like a super-cheap CD player, as my Nexus 7 definitely has.
I'm, let's just say, absolutely loathe to consider buying any Apple product ever again -- but, let's face it, iOS has an all round superior third party market system in place and Android STILL doesn't have any practical quality audio options that don't involve hinked up protocols like Bluetooth.
If the Android ecosystem doesn't address this issue it will, as tablets become more important as media gateways, sink to the lowest tier of consumer desirability and quality.
And that would be a real shame. But it looks inevitable as Google diddles and the aftermarket dithers. (And I don't mean the anti-alias kind.)
