Inverted Amplifiers

Several questions relate to this subject, beginning with: can you hear a difference?

To further explain Elizabeth's comments, an odd number of gain stages will invert the phase, an even number will retain the input phase. And as Stanwal states, an inverting preamp/line stage can be corrected by reversing one end of your speaker leads. But that will change all signals feeding the preamp as well. If you have a separate phono stage and it inverts and you also have other sources, that should be corrected by reversing the hot and ground connections on the cartridge.

For your subwoofers, you have two choices. Contact the manufacturer of your amp and ask if it inverts. Or test by ear as Al recommended. If you are not familiar with phasing, some test CDs (Stereophile's for one) provide a repeated track recorded in phase and out of phase. Listening to something like that without your subwoofers active may help to identify what to listen for.

Many thnks to all of the commentators! Your information should help me get the most out of my system.

I had and HAVE a pre with absolute phase switch.
Some material it can make a difference, but for R+R, which has had the phase data beaten out of it, it makes no difference. Multi miked anything is almost alway a mess, as well.
The most difference I have noted is on Solo instruments and than it is subtle and clearly preference driven.