That doesn't even begin to make sense which means one of your premises is obviously wrong. Either your PA is not as good as you think, something is configured wrong, or you are not used to hearing a mic'ed amp tone through a PA.
Think about it. If you can record a miced amp and a digital tone and they sound extremely close, if you play those two recordings through a PA they should still sound extremely close. There is nothing about the original digital source that the PA will know is different. If a DJ was using the PA would you be able to instantly tell which studio recordings were done digitally because they would sound awful compared to recordings where amps were used in the studio? Of course not!
Now if you want to fix the problem, admit to yourself that you must be doing something wrong and figure it out. Maybe play some recordings through your PA. Do they sound very different? Do they sound crappy? If so, it's not the modeler.
If recorded music sounds fine, record something from Tonex that sounds good on your monitors and play that through the PA and compare it to the Tonex direct to the PA. If they don't sound the same you have a configuration issue.
There is absolutely no reason Tonex won't sound as good or better than any other digital solution OR mic'ed amp through the PA. Enough of us have done it, and tons of people are doing it every day.