I had two rack systems at different times, and wish I still had both. I had the ADA, and I also had a Digitech Twin Tube preamp. They were both very good. I got the ADA for CHEAP ($75) and thought to myself, "Is this going to sound as good as I remember? Or I am looking at the past through rose colored glasses?" No. The ADA is that good. I think the Digitech was a tad more versatile due to the graphic EQ, but the ADA is a great sounding preamp. I don't think you'll find one for the deal that I got, but they can be had for a reasonable price. Just get the changeable battery mod for the memory.
I had to open it up and re-adjust the gain trim pots because someone had it so dialed back that you had to dime the gain which is not the case with an MP-1. But alas, I am here in Atlanta where everyone is seemingly trying to be the Allman Bros. reincarnated. Not a bad goal to shoot for, but it doesn't have to be VERY guitarist you see either. So I think someone dialed the trim pots way back instead of just adjusting the gain from the front panel. There are some very good in between, and semi distorted tones in these tings as well. It just takes a little experimentation.
Although I have never owned one, I have heard more than a couple of the Marshall JMP-1s and they sound pretty darn good too. I would say that you might also want to look at a Digitech Twin Tube as well. It's a pretty good sounding unit that also has delay, flange, chorus, and either a 7 or 9 band graphic eq. You can pretty much get anything from a Mesa Boogie to a hot rodded Marshall with it as well as some nice cleans and on the verge tones. The only problem I had when I first bought it was that I thought you could run the effects simultaneously. You can't. It's an either or. Oh well. Quadraverb to the rescue!
