Audiophile-PMPs are a pretty rare breed, especially if you don't want to empty your entire bank account to acquire one, and so the Nationite S:Flo2 has plenty riding on it. Priced from $119.50 (albeit only netting you a mere 2GB of storage), the S:Flo2's selling point isn't its touchscreen, video capabilities or games, but its excellent audio quality. Joker of the MP4Nation forums has reviewed the S:Flo2, and it turns out you really don't need to spend crazy money to get crazy-good sound.
Firmware and the UI in general are a little buggy, apparently, but that's more than made up for by audio Joker describes as "transparent". That means very dynamic, clean and clear, with a flat spectrum and - thanks to a rotary volume control - you don't even need to turn the capacitive touchscreen on (which can apparently introduce a little buzz) to tweak the output.
It's worth pointing out that the rig in the photo above is the S:Flo2 strapped to Joker's DIY mini3 amp outputting to a set of Beyerdynamic DT770/250 headphones; the actual PMP is far more iPod touch like on its own. Not for the mass market - as you might expect, shoddy quality MP3s will quickly get shown up by this particular mediaplayer - but a reasonable choice if you're looking for audio performance on a budget.