I bought the Luxman L-590AXII last year and i agree with this. I own the Harbeth SHL5+ and find the Luxman/Harbeth match to be too polite and warm for my taste. I find the Naim to be a better match to the Harbeth.
i would agree with the above
harbeths like an amp to grab them by the you-know-what’s and make them sing
more efficient devores may not want/need this quality in an amp sound their best
as usual, system synergies prevail in a specific application
in general though, if someone is used to a wavac/shindo/air tight/audio note tube sound, moving to top tier solid state amplification will sense something is missing from the beauty of the music