The previously mentioned issue about my DI20 exhibiting awful static, and R/L channel mismatch on the majority of power-up cycles has currently been resolved, and astonishingly - it seemed to be all down to DAC pairings!!
Just last week I got the new Chord Mojo 2 portable DAC (which includes a modest internal amp) and paired it with the DI20, and. 'WALA' - the first startup worked just fine. Assuming it was just a normal random chance that the DI20 worked right, I carried on and enjoyed the FANTASTIC sound, that IMO comes darn close to the Chord Qutest... it took me a while to notice that in fact the pairing is actually trouble free in the long run. Each startup works perfectly and quickly, including with sample rate changes.
This is literally the 4th DAC I have paired with the DI20, all previous of which have exhibited the above static and channel reversal issue, which I had been used to troubleshooting on a daily basis by power cycling on / off the unit between 2 and 10 times until the audio comes out right. The first DAC being Schiit Modi 2 multibit (for this one I can't quite recall if it happened less frequent or not at all), then was Chord Qutest, then iFi Micro iDSD Black Label as a DAC. All of these connected with RCA coax cables, with the exception of the Qutest which had to use a custom BNC to RCA cable to be compatible with its input. And now for some reason even though my new DAC is also from Chord Electronics and also using a RCA digital coax cable, the problem is solved. I have a hunch it may have had to have something to do with a digital handshake between the DDC and the DAC. Probably not significant, but the difference now being with the new DAC is that the digital coax cable is RCA on the DI20 side and 2-pin 3.5mm on the DAC side, for compatibility.