To keep it simple. My preamp (C2300) XLR's are wired different than my Marantz SA7-S1 CD/SACD player. So the signal that reaches the amp is inverted. So I have two choices, one is to use the electronic phase switch on the CD player or to flip the + & - speaker wires at the amp.
The biggest improvement I found was doing it at the amp end. When using the CD polarity inversion switch things improve, but the improvement is better when switched at the amp before the speakers.
Using the Polarity switch things improve, but their still is a mist and imaging is bloated not as tight or stable, vocals definition vague in comparison when I switch the speaker wire leads at the amp end.
This is what I noticed when switch at the amp end. Imaging improves, depth and field and width improves, micro dynamics and small details are much easier to hear almost like the noise floor drops.
The thing that will throw you off, is when you do the phase switch at the CD player, the sound becomes more forward and bigger sounding, so at first you think that is better, but if you really listen to a vocal, a trumpet, snare drum, yes it does sound less upfront when switched at the amp, but the attack is clearer, words are clearer, and instead of big a bloated big image things tighten up and have shades of micro dynamics.
I use a mono recording also, and in very case switch the amp side of the speaker wires gave a much more natural and real presentation, though some might say less impressive hi-fi sounding due to the depth of field and imaging moving from the front of the speakers to behind the speakers.
This has been written about for years, Martin DeWulf wrote many articles on this, and others have also noted that switching at the amp is better than doing it electronically at the preamp or cd player.
No all this does it get your system in proper absolute phase, recordings still can have issues. and then phase switch on the preamp or preamp will assist in that issue.
Having said that, it is also know some speakers my not show these changes due to their design. My my speakers do, and it takes seconds to hear it and once you hear it and train your ear you become very sensitive to it.
We could open another can or worms talking about AC polarity affect on certain audio designs. Sony SCD1 for instance sounded night and day better with the AC male end polarity switched.
In fact many books say all your gear should be checked for this to make sure your really hearing the gear that you paid your money for.
Simple cheater plug, file off the thicker prong, then just reverse the male end, one will give you more stable image, better bass and attack, and a much more musical presentation.
The other vague, boring, and somewhat lifeless. I think a review in TAS just mentioned this on a unit they reviewed, saying make sure your flip the AC polarity on the power cord.
Like tuning up a motor in a car, getting your system at peak performance takes some effort, and in the end you will have piece of mind.
