@theFixer
If you can possibly try one before buying is a good idea as not all valve pres are equal.
I tried to go down the valve pre into SS amp to save myself money and weight but the pre was frankly 'fizzy' sounding. Made me realise how good the valve pres in my old mosfet hybrid were.
Alembic and Fender both make or made stand alone valve pres. There are also exotic beasts like the Jules Monique, but they are 1. costly, 2. specifically designed NOT to overdrive (where's the fun in that?). A search of the FX forum will find you much discussion of the merits af various valve pres, but it has to be said, NOTHING beats the sound of output stage distortion ... and an old Peavey or second hand Traynor will get you there for only a minor body part or two.