Dared MP-7 Output Impedence and 15 ohms' speakers

OK, apparently I can - but when parallel wiring to reduce 16ohms speakers to 8, will doing it twice so to speak (as there is a positive and negative cable coming from each amp tap) thus 4 in total mean the final impedence will in fact be 4 ohms as opposed to 8?
The only parallel speaker wiring diagrams I've seen show two wires one pos and one neg.

Haw many speaker systems do you have? Just what are you intending to wire in parallel?

I'd hook one speaker system to the 8-Ohm tap of each amp and listen. Unless the speakers are REALLY sensitive, you won't get much volume with 6 watts.

One tube amp two speakers both 16 0hms but the amp only has a 4 and a 8 ohm tap; I dont want to lose the power from the amp so thogoght parallel wiring would work to reduce the impedence of the speakers from 16 to 8 ohms.

But the configuration will always be two speaker cables coming from the amp to the speakers each of course having two wires; thus will the positive to positive parallel crossover connection from speaker to speaker have to be done twice? All diagrams I've seen only have two single wires.