Pioneer Amplifier 380WRMS @ 4 OHMS is suitable
Kenwood Kac 8104d - 300wrms @ 4 ohms Suitable , 500Wrms @ 1 ohms not suitable
Kenwood KAC-7204 - 500Wrms @ 4 ohms in not suitable
the reason why i said , they are not suitable , cause once i was reading pioneer 308d2 manual ,it said clearly select that amplfier which should be less then its Wrms
means 400Wrms for 308d2 is pretty much , its not UNDERRATED amplifeir
try to give power below 400Wrms