Normally a two channel amp is a two channel pre-amp fed to a mono output amp, and from there to the speaker. What type of "two channel" amp are you referring to?
I imagine you've seen them on ebay. 15wx2 pre-built circuits. Not an amp, just a circuit, to be built into an amp.
“2x15” implies a 2 channel power amp. Designed as a stereo power amp. You could run mono in and one side out, but dual mono in and two speakers would use both channels of the amp. But you’re talking about a power amp that would work best with a preamp as well.
If your talking a two channel power amp then there is no practical reason use half an amp. You would end up with one amp running a 'load' and the other no 'load'
Now if your talking a two channel guitar amp. You can set each channel's EQ differently. Say one channel with scooped mids for a more acoustic sound. The other with heavy mids for a fatter rock tone.
Perhaps, but there is to be only one speaker and a mono input.
15wx2 is a power amp circuit, for home or car stereo, you will still need a preamp circuit to drive it. Those are only a few bucks on eBay as well.,,. Happy building!!!
You may be able to bridge the output of a 15wx2 amp to one speaker for a 30 watt output to a single speaker. I believe it depends on the circuit and output class of the amp.