I've been using a Tascam US-122MKII (pictured) because I needed the XLR inputs for recording. No idea how the headphone input compares to a traditional amp though. Oh, and by FiiO, I meant one of their palm-sized pocket amps. Possibly a bootleg since I got it on eBay years ago, but it didn't blow up, so I'm not sure anymore, though I still have it lying around.
I won't be upgrading my audio setup for some time, but I'll bear in mind amplification in the future, particularly on the logistics of a headphone>amp>interface>pc chain versus headphone>interface>pc. The weakest link in my audio setup is easily my noisy fucker of a laptop fan which I will be so happy to be rid of in the future. If there's one thing I miss about my old netbook, it's that it was virtually silent.