I have a Dual Pre..... picked it up at my local gear shop and used it a handful of times when I was without a pre last year. Seemed to do fine, I think it has a grounding issue or something though. I've been using it as a headphone amp running USB out of my lappy. When connected to USB, it seems buzz when I touch it. If I don't touch it, then its silent. Not the greatest amount of gain or anything, but it powers my Busman mics (not sure if it's true P48, although the owner of the shop that I got it from said it is... I think) Small, powers mics, either dual 1/4" or 1/8" outputs.
I didn't try very hard, but I never did figure out if it can be used as a front end for a lappy via USB. I know that you can use it to monitor playback on a computer via USB..... just not sure about the other way around. I was told that it does not have an ADC..... not sure how that's possible since it has a USB?.... unless the USB is just a DAC.
The front and back plates come off fairly easily, but I didn't pull any of the "guts" out. That would be sweet if it could be upgraded by a few mods! It has some purpose for me, so I don't want to "kill" it..... but if someone can upgrade the chips.......
If you want to check it out Nick, let me know.