Matching tube preamp to ss amp

There are a number of tube preamps  within your budget that have a lower output impedance. Jolida, Aric Audio, Quicksilver, Atma-Sphere, Van Alstine, Rogue, and others. 

Otherwise look for an amp with higher input impedance. Either way when changing amplification, I would improve on the impedance ratio.

Giving your speakers are not attempting the lower octave you may not be hearing a problem with your current matchup.

+1 @mesch .
For a modern preamp 2800 ohms is high. 

Actually 2800 ohms isn't bad- what's important is the output impedance at 20Hz; the 2800 ohm figure was probably at 1000Hz. If the output impedance at 20Hz is greater than the 1000Hz value (which is common unless the preamp does not employ an output coupling capacitor), you will experience less bass impact with the NAD.


This is one of the reasons tubes get docked for bass relative to solid state. But its more a matter of properly matching components than whether tubes can play bass right or not!