Sound stage, front, middle, or behind your speaker

Polarity for one is the reason it is in front, or behind a dipole speaker.
One of the interesting things about a dipole is the way the soundstage moves from front to back when the polarity is reversed.

I agree with Elizabeth. I'd bet that if you swapped the negative and positive speaker leads on each respective amplifier channel your presentation could move more forward. You might want to try that to see which way your recordings sound best to you... Be sure to do the swap on both channels or you will get an out-of-phase result that won't sound right.

Actually I like all smaller groups in front. and big Classical orchestras 'behind'.

I prefer an image behind the speakers in an (ultimately futile) attempt to create the illusion of sitting in a concert hall, with the performers some distance away. I generally sit mid-way or 3/4 of the way back in a hall, and I want the performers to seem to be an appropriate distance from me.

It may be entirely psychoacoustic in nature, but I position my speakers about midway along the length of my room so there is a space behind them for the musicians to "occupy." I want my ears to tell my brain something that it is impossible for my eyes to tell my brain. Crazy, no? But it works for me, and it works with a variety of different speakers.
-Bob

Elizabeth... does that mean you switch your speaker cables depending on what recordings and types of music you're playing?

Both my amp and DAC feature polarity inversion on the fly, so I have no problem pushing a button on the remote to get the preferred presentation for a given recording. Too bad the majority of equipment manufacturers don't include the polarity invert feature as standard. They apparently think it's inconsequential, but I disagree based on listening to many recordings both ways.