As a reference, the DMP3 is a slight upgrade over Mackie VLZ preamps IMO. But if I already had a Mackie, I wouldn't go out and buy a DMP3. Haven't heard of Soundtech.
I don't know if the pre's from this mixer are as good as a mackie, but they are probably somewhat comparable. Maybe I will use that money to buy a couple of SM-57s and stands, and save up for a FMR RNP.
I have an old Behringer MX802 that I use for headphone monitoring. The DMP3 pres are a big improvement IMO (much less strident, more depth and better imaging in the stereo field).