Something immediately comes to mind about older equipment. Some older equipment had a mechanism that allowed the user to reverse the phase of the output by changing a switch, or rear panel setting. What it seems like you have done is reverse the phase by switching the speaker wires. If there was such a setting on the amp, and I don't recognize if this model does, and it had been changed, what you have done is to put the speakers back into the correct phase.
Just a guess, but you might want to look into that possibility. The other factors are the new acoustics of the new room/house, and that you have changed amps driving them. Another thought would be what is know as "psychoacoustic phenomena", or simply you became accustomed to the sound before, and now it is different....also known as "it is all in your head". ;)
The fact that another person hears the same "anomalies" leads me to believe it is something tangible, as noted above, and not your imagination.
Regards,
BBIBH
