I think most DACs have optical input. At or below your price point, Schiit Bifrost, Wyred for Sound DAC1, both of these have reputedly great USB implenmentations. Above your price point, the Benchmark DAC1 USB also has a great rep for USB (and the pre-amp output). Most other DACs at or below your price point do not have decent USB implementation, or so I've read. I bought a PS Audio DLIII because I knew I'd prefer the warmth it's supposed to have, and it's supposed to handle low frequencies quite well. I haven't been disappointed, but I had to buy a USB/SPDIF converter to get the USB sound quality up to the same level as that coming from my Denon transport.
At your price point I'd definitely give the WYred for SOund DAC1 a try. It would have been my choice if I'd had the dough. Other choices: Peachtree DACit (wall wort), the Rega DAC, the Arcam unit, Music Hall 25.2 or 25.3, MHDT Havana, Cambridge Audio DAC magic (wall wort), cheapest option with the best reviews would be the Emotiva XDA-1. Music Hall also has a DAC 15.2 that I heard at RMAF and liked. Your options are wide open with optical as the input, everyone's got it.