I'm trying to decide which amp to go with and the xdi 600.4 and the pdx-f6 look almost identical except the alpine cost a couple hundred more.. Anyone heard both of these, which is cleaner? I'll be runnin hertz hsk 165 components up from and hertz hcx 165 coaxial in the rear with the amp I choose.. I do have an old American made precision power pc4100 that's 100x4 but I'm looking to free up space and that precision power is huge... Also will either of the two amps I meantioned even compare to my precision power amp? Thanks for any input