Putting it in the tape loop allows you to more easily bypass its A/D/A conversion should you choose to do so for some reason. So the tape loop may be the most convenient way to hook it up for evaluation purposes. If you find its A/D/A + DSP beneficial in all cases after an evaluation using the tape loopthen between pre and amp would make sense.
Also, between pre and amp, if you are using it as a DAC, aren't you bypassing your preamp's volume control (and any other benefits the preamp provides)?
Also, between pre and amp, if you are using it as a DAC, aren't you bypassing your preamp's volume control (and any other benefits the preamp provides)?