Ken,
To confuse matters a bit more
If you are using the analog outputs of a modded SB3, that also inverts the phase. Running those outputs through the Candella puts the phase back the way it should be. If you use other inputs, CD, DVD, etc, the phase will be inverted from them.
I would choose a track with good center vocals and listen with the speaker wires hooked up one way and then turn the amps off and reverse them. turn the amps back on and listen again. Remain with whatever sounds best to you.
Nothing is easy.