I am running the P1s with a balanced cable on the R3, and it's a great pairing. I don't notice any of the noise that was noted above, I think the Andromedas are more sensitive (or particular). The nice thing about balanced is that it also feeds the P1s extra power, which they thrive on. It's much better than straight out of my Cayin N3, which I think is somewhat comparable.
If you can find a nice balanced cable and get an adapter for those times you are plugging into something that's not balanced, I think it's a great upgrade.
Thanks for the feedback about the balanced cables - I think you saved me from cutting off the cable and soldering on a TRRS plug...
With regards to the R3 vs Cayin N3 I have a different impression. Actually I find the N3 to be a really nice player with a very natural and smooth presentation.
The R3 is without doubt the bolder one, and when switching back and forth it always impresses with clarity.
When I switch back to the N3 however, I really enjoy the smoothness and refinement.
I actually tried to tame the R3's processing with the MSEB, but never got it to really smoothe out.
I really wish there'd be a setting to get a more natural sound from the R3, because it seems that the underlying signal is clean and of high quality.
In a private discussion another head-fi reader shared the feeling of over-processed sound coming from the R3.
Reminds me a little of the way TV sets are set up at the shop - with overblown colors, sharpness and smoothing out of texture. I think most people would set them to a more natural picture style at home.
Long story short - the really nice UI and size/shape make the R3 the perfect transport for my Mojo, the N3 would be my preference for sound, so I guess I'll use it as a transport in the car or give it to my son