Best input nac 202 for Rega phono pre

Any of the inputs are fine although you might wish to choose Aux and maybe avoid one of the AV inputs.

Thanks Richard - is there a difference in sensitivity or quality?

at the moment it's plugged into the phono plug av socket because at the time I had spare phonoleads to use

why would tuner/etc be better?

Avoid the top Aux2 pwr input as it also provides power to a stageline.

10.6 of manual refers & is normally capped

No difference in sensitivity and quality should in essence be the same too although some reckon that some inputs sound a little better than others, probably due to the routing on the PCB.  You can always try for yourself, and if you hear a preference fine, and if not, that's fine too.

Try to use RCA > DIN for connecting Rega’s phonostage to your NAC.

Yes, as Adam implies above, try to use a DIN input as it sounds better than RCA phono.