ok I'm looking for an amp (head or Pre/power) that will produce a big low end and has a LOT of power. currently i have a GK 800rb and it just dosen't produce enough low end to my liking. the speakers i am using are an Avatar 4x10 and an unknown 2x15, the cabinet is fine but i need to replace the drivers because they arn't that great. i also still want to bi-amp the system my questions are: what head or Preamp will give Massive low end, and also give me a lot of power and head room with out to much money (if its not obvious i am very poor i was looking into an Ampeg svp-pro pre-amp (i think thats the one), with a crossover and a Nady 850 and 1400 power amps to power it.(850 for highs to the 4x10 and the 1400 to the 2x15) which brings another question: Are Nady power amps good? i was wondering because they are rated for so much power and are extreamly cheap. i am very confused any suggestions on what preamp, power amp, or head. please help me!