if you run 2 woofer on 4ch , u will be having Loss of quality from PRE output
prevolts will be divided , if in parallel to the channel , u wil be losing current aswell in pre volts
therefor its better to have powerfull 2ch ,
or mono block for 2 , 3 subs
this is the reason 2 subs shouldnt be played with 4ch amp
either evo,sa and other powerfull brands
but some 4 amplifier , comes with Input selector mode , that is 2 RCA can be used with same input in 4channel amp
if its not present , then using T divider to reduce power from pre , REDUCES QUALITY + POWER from amp