Installing Subwoofer, Amp, High to Low Converter to stock radio 2010 Honda Civic?

[planar]

i have a 2010 honda civic lx. i recently bought a 10inch kenwood sub , a 2 channel crunch amp, and a high to low converter. i realized my stock radio didnt have rcas so i bought a high to low converter. everything is installed and worked good first few days. Nowadays when i turn it on and bump some music i hear the bass die down, or sometimes even when i turn it on, i barely get bass. i checked all the wirings there good. could it be that i connected speaker wires with black tape? or do i need another head unit? please help