the first one is not really good, since its trying to be a car amp as well...... trust me EQ's trying to be amps suck!
same with the second one!!!
my advice, get a GOOD quality pioneer/clarion/etc.... preamp/EQ/sub crossover/fader half DIN unit.
run the computers output into the EQ/preamp, then outputs to PROPPER car amps, and your sub amp.
otherwise just split the computer sound output straight to your subamp and another amp for your full-range speakers. then use winamp's inbuilt volume and EQ controls......