I have owned two Sonic Frontiers pre-amps...I would recommend both. They are line-level tube units and both are within your price range for a used one.
The SF Line 1 and the SFL-2 (an older model) both have balanced and unbalanced ins/outs and use 6DJ8 type tubes. In my system, I found the sound quite neutral and perhaps a little dark sounding, transparent with well defined detail and very good bass.
I've used them both with solid state and tube amps with excellent results, however, with a tube amp the sound was more pleasing and musical to my ears.
Supratek's are great so is the Bent unit (good luck finding one).
Happy hunting!!
The SF Line 1 and the SFL-2 (an older model) both have balanced and unbalanced ins/outs and use 6DJ8 type tubes. In my system, I found the sound quite neutral and perhaps a little dark sounding, transparent with well defined detail and very good bass.
I've used them both with solid state and tube amps with excellent results, however, with a tube amp the sound was more pleasing and musical to my ears.
Supratek's are great so is the Bent unit (good luck finding one).
Happy hunting!!