speaker level

I have a phoenix gold 10” under seat sub. I have spurred a high level signal from one of the rear door speaker’s to feed the signal for the sub. Now I know that some will say take a feed from both sides but to be honest doing just the left was a right headache so can I connect the spur to both...

Hi all,  New to the forum - doing my 2nd install, upgrade to a Chevy Bolt.  Generally, one puts passive crossovers after the amp, but is there anything preventing me from putting the between amps?  I will be running speaker level outs into my aftermarket (Sony) amps. Seems like it would be...