What I would do is try using the s/pdif out from the tascam once, and then try doing the exact same thing using analog out of the Tascam (without any A/D in the Tascam if that is possible on your machine), and letting the Maudio do the conversion. Listen closely to the results and see which sounds better. If they sound the same to you, then as a matter of principle I would use the Tascam's converter to save an additional level of conversion. It is also possible that there is no way on your Tascam to output an analog signal without a complete a/d and d/a conversion. The manual should be able to help. One way that almost always would be purely analog (no conversion) is if you outputted your signal directly off the insert jack.