Al, even Steve Nugent from Empirical says his Overdrive DAC (when fully loaded) does not benefit from an OR5...for him to make that claim (as he also designed/sells the OR5), shows that as DAC designers pay more attention to incoming jitter, we have less to worry about with respect to the incoming signal. That said, audio via USB, through a PC (sorry Mac guys)...there appears to be a lot of benefit using a specially designed USB card in the PC (low noise, with the appropriate linear PS)...this is SOTA server development in the threads I have read over at Computer Audiophile.
A year ago, I would have said that ANY chains benefits from an OR5 and it is still a very good device...but now the game has stepped up a notch and I thank Rob Watts for saving me that money...a fully-loaded OR5 is close in price to that of a Hugo. Likewise, Steve at Empirical is doing a lot of development "post-DAC" with things like the Final Drive. Interesting times indeed.
I still want to try a TU-5 tube (the little portable one) after the Hugo to drive my TH900's in the "ultimate" portable rig; as I'm concentrating more on the post-Hugo chain than the pre-Hugo chain.