A short post- review of the NP1.
As always, the opinion is based upon to "our ears (wife and I), our room, our preferences blah, blah blah. YMMV
We found, like almost all equipment, the NP1 benefited (as well as suffered) from system synergy.
With streaming with iFi Zen streamer, Gustard R26 Dac, NAD C658 as preamp and Dirac processor into GoldenEar Triton One speakers- we felt that the NP1 played all the notes but was a bit flat and two dimensional. Low level listening was somewhat uninteresting. Listening at moderate levels was pleasant, but didn't draw us in.
We then changed the NAD to fixed output and inserted a Schiit Freya+, outfitted with vintage GE and Sylvania tubes. The tubes tested "as new" rather than claiming to be New Old Stock.
Re-calibrated Dirac with new setup. The overall sound of the system now sounded superb: Low level listening, moderate volume, high(ish) volume- everything was more holographic, vocalists and instruments sounded real and in the room with us. Presentation was neutral to very slightly warm. Not at all fatiguing. Before, we were considering returning the NP1- now, it's staying and we're excited to try it with other speakers in the collection.
Some other amps in my collection include: First Watt SIT3, PrimaLuma Dialogue Premium (KT150 output tubes), Hypex Ncore 400, Sony VFET TA-5650, Concept 11.0 and many more..
The combination of Freya+ and AVA NP1 doesn't take a back seat to any of the above. Is it "the best"? Probably not- but the combination is more than worthy and highly recommended.
I could write more, but trying to keep this short.