Can hardware change speaker phasing over time??


After years of great listening, I suddenly noticed I wasn't getting the sharp center image with vocals.  I spent hours moving the speakers and even did Room EQ on my Denon receiver (which normally would tell me if speakers are out of phase). The vocals sounded diffuse.  Finally, I switched the wires on one speaker.  BOOM!  Right back to crystal clear center imaging on vocals, on all of my favorite tracks.  I've checked all the wires.  Everything is hooked up right, though now red is hooked to black on one speaker.

Could something have changed the phasing in the hardware?  There is no other place in the set up the wires could have been reversed.  I have triple-checked that the ++++ cable is connected to the red output on the amp.  

Signal goes from Mac Mini by USB to Bryston DAC, by two single channel cables to Denon receiver, by two single channel cables to Parasound A21 Halo amp, by speaker wires (one wire marked ++++) to B&W CM10s.
stroud27612
:-)   Is that movie really worth watching???  I'm on the edge.

The trick here is that the wires really didn't get switched.  They were the same as always, but just started sounding out of phase.  Once I switched one speaker, that solved the case for sound.  But the speakers are now, technically, wired out of phase.

Hence my query of whether the phase signal could have been changed somewhere in the Denon or the Parasound amp?
There’s parts that are really, really well done. There’s parts that are heartfelt and inspirational. There’s parts that are basically fart jokes. Because it is after all a Will Farrell movie, so get real. The songs are the highlight. The opener is as good as anything from ABBA, and I actually like ABBA, and this is that quality, only funny. A lot of the songs have double meanings. Jaja Ding Dong seems like a funny Icelandic ditty until you catch "my love for you is growing wide and long" which if you think about it is pretty explicit, and the running joke about him being in love with his sister, Pierce Brosnan being a Lothario who fathered half the town. Also the contest political stuff is really well done, the banker pulling the strings, etc. So basically about half good gags, half good funny music, half potty humor. Typical Will Farrell, up there with Blades of Glory. (What do we have that the others don't? Matching junk? Right!) 

There’s simply no way any hardware caused a polarity switch in the speakers. Other than elves, I mean. But you do have a receiver, inside which all bets are off.

When properly set up the difference between in and out of phase will be more than just vocals being focused. When playing a mono track in phase everything should be coming right from the center. Nothing anywhere else. When playing out of phase the mono track should be coming from everywhere. Not only is nothing coming from the center, nothing is coming from anywhere. The sound is so diffuse there is nothing you can point to anywhere as the source of any of it, vocals, instruments, none of it. I forget the Stereophile CD but the XLO CD has a track recorded mono to do this test.

From what you’re saying its almost certain one channel did get reversed somewhere, some time. To track this down, follow the signal path. Plug earphones direct into the Mac mini. Then direct into the DAC. Use an adaptor, or sacrifice a cheap interconnect to get at the wires and hold them on your headphone plug. These connections only need to be good enough to hear if its in or out of phase. Which should be pretty obvious.

My bet is one of your three digital devices (I’m assuming the receiver includes a digital processor of some kind) messed up and needs a reboot. But mostly because otherwise we are back to the elves.
I am in the process of figuring out what s up with my 20 yr old Thors,, I just bought new Millennials tweeters, will arrive next week from Madisound,, Madisound just built new xovers with high quality parts,, but not sure if
A) recent mods bya  local tech on the Jadis DPL Linestage is the issue
B) the Millennials are going bad(just spend $100 for new voice  coils
C) the new xovers just are not as good as the old Hovalnd xovers.
So had all hooked up, and turned it on,, 
Disaster, Completely gone that gorgous Jadis sound, sounds like sh*t.   
Have 2 new Millennials on the way,, Tech guy wants me to swap out tweets BEFORE he chnages his mod back in the Jadis DPL to original design.. 
costing me $$$$$$$
I suggest you try new voice coils in the tweets.  They are  like $50 each.