Try it.

I'm in my third decade of using amp modelers and if it's one thing I've learned it's that the live sound you get is REALLY dependent upon the matchup of modeler and power amp I/O more than anything else. You can anticipate speaker/cab responses but the I/O matchup almost comes down to serendipity. Something like an ART TubeMP (or better, naturally) between the modeler and power amp inputs can go a long way to leveling the I/O playing field.

I don't have a TonePort, and I haven't used Line6 for the better part of a decade (with the exception of one recent gig while my other modelers were being serviced). Here's what I do recall:
(1) I don't recall the TonePort as having I/O level switches (+4/-10dB) so that might be an immediate issue.
(2) Check your TonePort's software output setting. Oddly enough, you'll probably want to start out with Direct settings (turn the cab modeling off). Add the cabs as needed.
(3) If the TonePort has the mic option, start with the distance at zero for the most defined sound. If you can't seem to get all the clarity you want and/or get rid of all the reverb you want, the mic distance is probably the culprit.

Good luck,
Paj
8^)