I play my N3TLs with my Onix H6550. It sounds great. I don't go past 25% on the volume and I use a 5771 input tube vs the 12ax7 which means I have a lot less gain. I also have a nice Denon reciever and while it has more high end detail it is not as nice to listen to. Meaning it just doesn't connect in the same way as my tube amp. Plenty of bass from my tube amp.
Here is the thing with these speakers, look at the impedance sweep they are easy peasy to drive. Tube amps love a speaker that does not dip too much and has high enough sensitivity that you don't need a bazillion watts to reach reasonable spls. Infact, I specifically chose this speaker with tube amps in mind.
