Is it ok to use only a single channel of a 2-channel amp to connect two speakers in parallel?

Question

Amplifier is 800w at 8ohms, 1350w at 4ohms. speakers are 400w rms at 8 ohms

Answer 1

Not at all. Why not just use both channels and bridge the inputs so both output the same signal. That would accomplish the same thing.

Answer 2

you'ld be at a 4 ohm load, but even then, I can't understand why you wouldn't want to utilize the other transistors in the amp? you want current, requires amps, try it both ways, you'll see.