I've got both of those (well, the ART Digital MPA (gold in color), which is essentially the same thing) -- it's a huge improvement. The TubePre is a "starved plate" design, while the MPA actually fires up the tubes to specification voltages. I was able to get a decent low gain sound out of the TubePre by not really using the tube part, but unable to get any good tube-y sounds out of it. The MPA Gold is much more versatile, better sounding, provides more clean gain, and also has variable input impedance, which can be very useful.