Ok, you are warned, I would not buy a Ruku Soundbridge until it is clear that someone here actually has a running recent version of mt-daapd/firefly on his WL-700gE. Several people say that they have, but none of them has actually tried a Roku Soundbridge, as far as I know.
The Roku complains about Twonkymusic not having a search method (admitting it does not have one of his own), so it needs the power of Firefly. The Noxon audio 2 works flawlesly with Twonkymusic, but can't understand mt-daapd. They are mutually exclusive, so to say. Furthermore, if I have both Twonkymusic and (the 2006-stable version of) mt-daapd running, the Roku only sees the Twonkymusic-server. Only if I stop this server, mt-daapd shows up, but is regarded as not compatible by the Roku.
Marc