i got 1 pioneer 3600 reciever, pioneer 4 way 220 watt max 50 watt rms speaker and lightning 450 watt max 50 rms @ 4 ohm amp.im using amp for front speaker, im getting a pair of pioneer rev 6x9 in the back, its 80 watt rms, 330 watt max, now i need help with wut amp i should use for the new speaker?, should i use the old amp for it and recievers amp to power the front speaker, or get a better amp for the back speaker, and wut power amp thx