Can anyone recommend a fairly compact (but doesn't have to be travel-sized) DAC + preamp or headphone amp with an optical input and a volume control for under $100? Most of the ones I've seen are USB-only (Fiio E10, Schiit Fulla, Topping TP30)   Not looking for super high-end audio quality as...

Anyone with experience with both of these phones have a favorite? From reading reviews the NAD seem to have a slight edge but I've been pretty pleased with Sennheiser stuff in the past. That said I also have PSB Synchrony's powered by an NAD M3 for my main (non-headphone) setup, so clearly I...