Re: Boosting a Plexi
Bemused that people leave out the Boss SD-1 or the various MXR preamp/ODs. Which were the other major sounds of 70s to 80s rock. SD-1 is definitely better suited for OD use than the DS-1, more output available with less grit. But still has a mid-focused overdrive sound, though not the same one as a tube screamer circuit. Different EQ. Tube screamers are such classics for 2 reasons: the bass cut is just right for tightening up a lot of amps that get bassy at volume, and the mid boost fills in right where Fenders tend to need it most. But not every amp has that Fender preamp with scooped mids...
Rats have their following, too, though the ones I messed with I couldn't make heads or tails of with the amps I was using at the time.
Then there's all the more dynamic fuzzes, which at their smoother settings can be hard to distinguish from an OD/distortion.
There's a lot of nice modern variations that add in 3 band EQ, or switches to turn the low cut off, or put in a low boost instead.
I'd tend to go for a flexible OD like one of the Tims. The low/high controls on it let you cut bass & treble and boost output if you want a mid-boost. Ridiculously flexible once you get your head around the way the controls work. Really great EQ for guitar, in addition to being a great sounding boost.
+1 on jpage's Chase Tone props. Their Secret Preamp is said to be the best EP-3 preamp around. Less noisy and bulky than the originals, more accurate to original behaviors than other attempts. If you are a fan of Blackmore, EVH, Eric Johnson or so many others, an EP-3 was always present in their old live rigs. And it's an always on preamp, whether they were using the tape echo or not.