Crossing Left and Right Speakers

That usually occurs when you have the speakers wired out of phase. I know you said they were in phase but just for kicks, humor me, reverse the leads of one speaker and see what happens. :-)

Doesn't make any sense to me either. That is why I suggested that you physically reverse the leads on one speaker. Sometimes strange things happen with electronics that aren't predictable. For example I've actually seen the connectors on a speaker mis labeled and cross overs mis-wired. My suggestion was just to insure that everything was connected properly absent any assumptions. Only takes a minute. :-)

Folks want to confuse absolute phase which can be inverted either by a switch on the pre-amp, source, etc. The result of a change of absolute phase is typically minor and in order for it to be heard the source (disc usually) must have been recorded 'in phase' and often its not, as often some cuts in the disc are and some are not.

The 'phase' I was referring to was the relationship of the speakers to each other which occurs when each speaker is wired up identically, i.e. pos on speaker 1 and pos on speaker 2 - negative on speaker 1 and negative on speaker 2. You can invert this phase relationship by switching the connectors on both speakers i.e. neg on speaker one to pos and neg on speaker 2 to pos. If you do this, and its commonly done to facilitate a tube preamp which inverts phase, you will still maintain the imaging that you had before the phase was inverted.

Since the OP is loosing his center image I can not but conclude that some where in his moving wires etc in shifting his amps that he has misconnected his stuff and now has/had the speakers out of phase (not inverted). Make sense to you? :-)

OP, FWIW, I misread and attributed to you statements about soundstage aberrations experienced early in this thread. Obviously I thought you were experimenting with the equipment and getting the odd results. My bad. I should have read the post more carefully. I should have been talking to jimmy2615 as he was doing the experimenting that I attributed to you.