As far as I recall Joule preamps always inverted phase (I owned an LA-100 MkIII), so changing the speaker leads at the amp output would technically place things in phase again. However, try it and see if it makes a difference. There's been lots of talk about phase inversion with equipment, recordings, etc. Some can readily hear the differences, other have to strain a bit to hear the difference, and still some others don't notice a difference at all.
