If you experience unwanted "noise" when you use a stand-alone preamp, please consider what your signal is and where you''re sending it.
Some people send the signal from their preamp to a mic input (they figure, "well, I''m using a mic!") on the board or recorder. This is in fact incorrect and could be the problem. The Tube MP and other ART preamps are actually intended to output a nice fat LINE LEVEL signal. If you send that line level signal to a recorder or mixer''s Mic input, that circuit will usually add more gain to the signal. Gain on top of gain will indeed result in noise. Please treat the signal as Line Level and you''ll be pleasantly surprised at your new clean and warm sound.

The same rule applies for guitar and bass players that use ART preamps as their front end. Send the signal from your preamp to a low gain input on your amp, or even a "loop return" jack which allows you to bypass the amp''s solid state preamp altogether.