I just wanted to confirm that Rune works perfectly with my HRT MusicStreamer Pro USB DAC (asynchronous).
Also it works great with my large FLAC collection on external USB harddisk (with its own powersupply).
The music sounds fantastic and without hickups. Before I was using Volumio but it had trouble scanning my music collection and had occasional hickups. Rune performs fast and solid so far, with great sound quality. I'm very impressed with the results I'm getting!