I have always wanted to ask this question but is very afraid it is not well-regarded. Is it sensible to try and get a tube preamp like PrimaLuna DiaLogue Premium Preamplifier to match with a Naim NAP 250 DR.
I have a Uniti Star and is trying to upgrade to NDX 2, but feel the preamp side is a bit of a cost sink. So thinking of getting a cheap but respectable preamp to try.
With regards to output/input impedance, does it seems to be ok with Naim solid states?
Theory has it that Naim power amps are specifically designed to work optimally with a Naim pre-amp. I would suggest that without a demo it would be a bit of a punt with no certainty as to outcome.
ear 864 second hand is an excellent match for the naim nap 250. Not easy to find a tube pre which matches naim amp. Not easy to try also because you need to have a modified cable( din/xlr to 2 rca).
I have tried conrad johnson, but bad results. Ear 912, ear 868, and ear 864 will suit very well.