vtb1 vs dmp3
Don't know if you're still following this thread, but I've recently looked into the same question and just bought the vtb1 last night (!!). Haven't plugged it in yet though (no time to install my soundcard yet) and can't make the direct sound comparison with the dmp3. But, there are a number of technical differences that you can look into here:
http://www.studioprojects.com/vtb1.html
http://www.m-audio.com/index.php?do=products.main&ID=e1f3fc161e0af5eb5ac80481dc5efffa
I'd agree with Cardioidpotent that the single vs dual channel is a big difference. There are at least a couple of other differences that I noticed:
The other major difference would probably be that the dmp3 has a single gain control for each channel, and at least the info on the above web page doesn't indicate tube amplification. The vtb1 has a more complex amplification system that uses both solid state and tube amplification; the amount of tube amplification added to the signal can be varied by the user. There's also an output level control. It seems that the extra crud with the vtb1 might be good or bad, depending on what you're looking for. I actually wanted to pick up a dmp3 last night because posts on this bbs seem to suggest it provides very clean amplification. Who knows, maybe the variable amp control on the vtb1 allows for more flexibility in sound though. I think the manual also says you can effectively eliminate any coloring by the tube, if desired, simply by turning the tube setting all the way down. I think the final amplification provides around the same amount of gain in the end though, at least according to the manufacturers.
The vtb1 will probably be selling for a little cheaper; I paid $200 CDN for it.
Both supply equal amounts of phantom power, both have a high pass filter (disclaimer: this info is from the specs for each preamp; I haven't tested their performance directly).
The dmp3 has (continuous) VU meters, while the vtb1 has (discontinuous) LEDs.
Hope that helps
