Most think that inverted and non inverted options on preamp is for switching back and forth for certain recording, although one can do this and it can have an affect, this is not the true nature of what it is for.
It is about matching components!
If your preamp is inverted then you should be (in a perfect world) using an amp that is non inverted.
Like wise if your using a preamp that is non inverted, then you want an amp the is inverted.
When there is a mismatch that is when reversing the speaker wires will solve the problem.
On some systems it will be noticeable on others, not so much. I have found when setup properly it can affect sound stage and bass, listen to female vocals will have more depth as well.