Determining polarity? and Modulus3A question also

I wonder if one can tell using a multimeter if their speaker leads are in correct polarity. I know with my Modulus pre-amp I am supposed to switch the cable polarity to make up for the preamp being inverted and at this point I cant tell an audible difference when I switch them.How would I do it with a meter?
Another question is about the gain in the Modulus 3A. The notches on the volume control are big steps for my Klipsch La Scalas with CD source. In the manual they mention older models had a dip switch to tone it down but then they deleted that to improve sound quality. Can I add something to the circuit to lower the incermental gain?
If you can't hear any difference due to polarity, (which doesn't surprise me) why bother?
Polarity will only be important if you are running other speakers with the Klipsch (sub or surround).Unfortunately you can't detect cone movement with these,but if you hook up another pair of speakers with visible woofers and play something with some bass transients you can tell absolute phase.just put your fingers lightly on the cone and you will feel it move out with the notes (or in).I built an inline attenuator box when I had LaScalas out of two high quality 100k alps pots.This is not the ultimate approach but definetly helped!

Have you used this? This is exactly what I am looking for. Is there any chance for sound degradation? Any more information you can provide would be great. Feel free to email me.
I use the attenuators at the inputs of my mono amps. They do not degrade the sound. They do reduce the noise floor and increase low level detail.