Admitting right off the bat that this reply is going to be rich with shameless self promotion, let me tell you about our new Earth Drive pedal. We're about 1 week from hopefully having these things ready and also having some good audio samples on our website to check out. The Earth Drive is very much designed with that sound you describe in mind, the sound of a loud push/pull tube amp being driven to the point of being fat and smoothed out but not gnarly and "distorted" sounding. Many of us find that there are home, rehearsal, and even gig settings where we simply can't drive our amps to the point of reaching their power limit, which as we all know is where an amp begins to sing. So this pedal was born as a solution to getting the feel and tone of a pushed Fender or even a Mac tube amp but at any volume. I wanted to take some of that overly clean sterility out of the sound when not pushing an amp, taking some of that ice-picky sharp attack off the top and beefing it up a bit. I also designed the pedal so that it isn't overly EQ'd like so many dirt pedals are. It's very natural and un-voiced so your guitar sounds like itself. But the clipping and overdrive characteristics are similar to the feel and harmonic content of a pushed Fender amp, sort of like a 6L6 type amp, but with a bit more juice in the harmonics so that it's almost like a cross between a 6L6 and a 6V6 (think Deluxe Reverb). Of course it's not the real thing, it's just a pedal, but it really does sound cool in this regard. Part of the tailoring of the pedal was with Jeff Mattson of DSO in mind because he has a very clean and loud Jerry-rig that covers the 70s and 80s quite well, but I wanted the pedal to help him with the pre-73 tones and definitely the '60s tones where all of Jerry's power came from tubes that were overdriven. So anyway, that's my answer. Hopefully in a few weeks there will be a few folks here that can offer their honest opinions of the Earth Drive, yea or nay, and provide a more unbiased report than I can offer.
Previous thread on the Earth Drive: