Tons of preamp pedals put these days, but a little harder to find some high gain ones. Tubesteader makes the sun keeper, which is an orange rockerverb 2 channel tube preamp pedal, may be more suited for doom than what you want but a good option. Also a couple of Mesa studio pres are in the for sale section here.
I've tried more than 20 high gain preamps and my favorite ones are:
Mesa Boogie Quad (really raw and in your face)
Mesa Boogie Studio (more scooped / modern sounding than the Quad)
Peavey Rock Master (Really versatile )
Kettner Access (The triaxis killer)
Rocktron Piranha (Love - Hate thing )
ISP Theta ( good and cheap sounding SS preamp)
The Axefx FM3 blew me away and I normally dont like digital preamps. Its an all in one small pedal board size. I run that to my KSR tube power amp through a regular 4x12 guitar cab. Not sure what your application is but its a great for a grab and go rig with a band.