+1 to penta..
People can suggest here, but its upto you to try.
Since you dont want a drive unit per se, more of an amp pusher. Youd want either of the following:
The first suggested one is the
cheapest, to expensive, to more expensive. More expensive does not mean it will suit you better. Try them, and choose according to your tastes and budget.
1) Boost - EHX Nano LPB-1, MXR Micro Amp, Gsonique Boosty, Xotic RC Booster
2) OverDrives -
Non transparent - Digitech Bad monkey, Ibanez Tubescreamers, Barber LTD Silver, Xotic BB preamp, Other tubescreamer clones (Cmatmods, Analogman etc)
3) OverDrives -
more transparent - Boss BD-2 (modded), Subdecay Liquid Sunshine, (NOC3 Pure Drive, Klons, Blackstone MOSFET Overdrive)
This list is by no means exhaustive! Good luck with your tone quest
