I have an old 97 a3 1.8 20v sport without bose. I changed the head unit to a pioneer bluetooth head unit (which i must say is a great unit) what i did was change the back speakers to pioneer 13cm i made adaptors for them to fit, that is fine however the question i ask is....are those speaker fine to run off the standard amp that runs the back speakers? also i disconnected the standard nokia subwoofer and am running an independant jl audio setup. Is this safe or will this end in a catastrophy? Thanks for any help in advance.