Preamp for Luxman MQ-38u

How about a vintage Luxman tube preamp like a CL-32 or CL-35?

Does Luxman Still import tube gear to the US?  I used to enjoy the rich full sound of their SS gear years a go when I owned a TOTL receiver.  It's a matter of how you want to the sound to add up as it were.
Asa general recommendation I prefer the sound of octal pre tubes like 6SN7s there are a number of pre amps around that you may want to investigate.  Maple Tree audio custom builds such pre amps. 
Atmasphere also builds -a unique to him- line of such pre amps configurable to your needs. 

Both in your price point- as usual no financial affiliation whatsoever

Luxman still imports tube gear to the US.

Not sure if Solid state pre-amplifier would be compatible?

A very nice Luxman CL-35 MKIII on E-Bay that's in your price range.