But, if PS Audio didn't make claims about it needing no burn in time, I wouldn't be concerned.
I don't recall if Paul claimed no burn in for this DAC, but with all due respect to him and some others who've become virtual friends on the forums, I think this DAC does in fact need burn in. I agree you should wait before starting to change anything else, but I still think it's a good idea now to go into your XP-10 instead of right into the Pass amp. I read Ted's comments about that volume level still being okay, but if it were me I'd take it out of the equation by running it's internal volume up higher and using a fabulous preamp like the XP-10 to take care of that.