In that case I think it would make more sense to just have the speaker outputs disconnect the internal speakers to keep each amp at the normal 8 ohm load.

Does anyone have any experience with the uPC1188H? The data sheet says 4 ohm minimum but every amp I've seen use these has 8 ohm speakers. The data sheet lists 8 ohms as typical. I have a Fender Princeton Stereo Chorus that I'm interested in adding some cabinets to. So I was wondering if I should wire those in parallel for 4 ohms each or have them disconnect the internal speakers.