This is my first post. I have an opinion. :-)
I have a Firefly server wired to my Roku M1000. My music is a combo of 320kb MP3s, and most recently FLAC files ripped with Media Monkey. I also use MM to populate my iPod Classic 160Gb.
The Roku went into my McIntosh MA6100 (recently refurbed by George at Audio Classics, Ltd. - wow, they are excellent people to do business with!) and out to a pair of Paradigm 2-way bookshelf speakers. Worked fine in the family room for background music, but at any volume level over nominal, the harshness came to the fore... so, how to fix?
I found a GW Labs DSP reclocker/upsampler on eBay for $200. I purchased a new old stock MSB Link-DAC III, Full Nelson version, for $500 on the web. My thoughts centered around the fact that the analog outs in the Roku were marginal, to say nothing of the onboard DAC. Signal path is Roku coax digital out to the DSP (dsp is reclocking only, upsampling is off). AES/EBU digital out of the DSP to the input of the Link-DAC. The Full Nelson Link-DAC has AES/EBU inputs and the upsampling board, which is engaged. Analog out of the Link-DAC to a Musical Fidelity X-10^3 tube buffer, into the McIntosh.
The result is stunning. I'm a bit speaker-limited right now, but I must say that the difference is night and day. I listen to a lot of Radio Paradise and SOMA FM; even the 128k streams have an open, airy quality that is amazing. Best result, of course, is playing a FLAC file from the Firefly server (Firefly transcodes to WAV, out via wired ethernet to the Roku).
I'm convinced. Then again, you probably don't have to spend $1,000 to get noticeable results. I'm happy, though.
I'm also convinced that the GW Labs DSP plays a big part in this equation, reclocking the S/PDIF signal out of the Roku. I have considered taking the DSP out of the circuit by running the coaxial digital direct from the Roku into the Link-DAC for a listening test, but... I don't want to mess with my illusions. :-)
Cheers, good luck!