I am noticing the dropout after 25-30 minutes on firmware 2.50. I'm plugging the Helix Rack SPDIF out to the SPDIF in on a Focusrite Sapphire Pro 40. Once it drops out, I have to reset the clock source to internal, then back to SPDIF on the Focusrite for the sound to return. It does not return on its own. I did not have this issue with the HD500x previously. Just thought I'd chime in to see if anyone else is monitoring this issue and still sees the problem as I do.