Just picked up a original Surface RT.. the headphone out of this thing is fantastic! has more output than my ipad, truly a bargain at 180.00. It will take up to a 64 GB micro sd card, plus a USB port. I know this it got a bad rap from tablet users, but as a audio/ video play back it's worth it. Yup, it is big for a portable audio device, but with the expansion available. I hooked my 500 GIG Passport drive, worked like a charm, was also able to get about 10 hrs of life on a charge.
You definitely don't need to hook up a amp to this, unless your driving something insane.