The method I've used previously is completely objective, as it needs to be if you're not sure what you should be listening for ! Start off by downloading SpectraRTA from Sound Technology and learn how to use it. Best if you can install it on a laptop and take it out to the car. I then used my (cheap) Radio Shack SLM as the microphone set up at ear level in the car. My Empeg had the frequency bands on the EQ set to some strange values - I'd recommend changing them to the normal octave bands of 32, 63, 125, 250, 500, 1000, 2000, 4000, 8000 & 16000 Hz to start off. Set the SLM to C weighting, play a CD of pink noise and tweak the EQ until you get a nice flat plot on the RTA. Do *not* underestimate how long this takes ! I think I spent almost two days tweaking my system last time. You can see some before & after pictures from my pre-Empeg install here. Result was a generally smoother sound that was less tiring to listen to. It called for some pretty extreme settings on the EQ, I know I wouldn't have been able to do it purely by ear. If nothing else, running a quick RTA will show you how far off your current system is ! Steve.