System: Cary Audio Design SLI-80 cranked up to F1 specs (and more) by/at the factory running Genalex Gold Lion KT88s, NOS Tung Sols and RCAs for preamps, AP Virgo IIIs, all custom solid silver ICs and speaker cables, Tice power conditioner; analog end is VPI Signature Scoutmaster and Benz Glider S lo output, Phonomena phone pre, couple of Shunyata power cords in there somewhere...
What streams? Like, MP3, AAC, WMA?
I kinda knew going in that this ROKU may be a little bit, um, underwhelming vis-a-vis the rest of the rig, but for $100 i figured it would be a start
A system like yours would certainly benefit from a better DAC than the Roku, IMHO.
I think you might be asking what file convention to rip your files in, which is certainly a good question. The answer is highly debatable, but I tend to prefer the lossless options which include WAV (I'd avoid this for type for the lack of metadata support - trust me on this one), AIFF, Apple Lossless, FLAC. I believe the three you suggested are all compressed file types (someone correct me if I'm wrong). You should also be selective about the software you use to rip those files (I'd avoid itunes and go with something like MAX for Macintosh, and there are many choices for PC like EAC or MediaMonkey - not much experience with PC's myself)
I thought the ROKU was marketed primarily to stream video, and did not have as well implemented an audio/digital section as something like the Squeezebox Touch. The latter has pretty decent jitter specs on the digital out. I'm not familiar enough with the ROKU to really comment beyond speculation so I'll leave it to others.