gee tiffy - that could be any number of things. take a look at your meters on the tascam as you play back the individual tracks. most of those should be kicking around -3. if those levels look good take a look at the playback level of the mix you made - it should be peaking around -3 to 0dB. if those look okay, take a look at how you are feeding the signal to your system - maybe a bad or misplaced connection. start at the beginning of the signal path and follow it through, and you will find the problem.