This is for adjusting the radio in the new Model. It may work on others also. From the factory the settings are horrible. My 2009 wrx had a similar problem from the factory clarion unit. And they are not easy to adjust. The model number in my car is CV629UM. You can see the # on the bottom right corner of the radio. Key in the ACC position. Radio off. Hold buttons 1 and 4 down and tap the tune button. The display should say Through Mode. That's it for that part. Now. Radio on. Tap the tune button. And set these Bass 0 Press Tune. Middle +2 Press Tune Treble +5 Press Tune Fader 0 Press Tune Balance 0 Press Tune Virtual Bass OFF Press Tune SND Restorer OFF Press Tune Vocal Image 0 That's about it. You will at least be close to where you want to be. Messing with the base and treble will be a personal preference thing. This seems to help a lot.
For those of you with the stock HU with the radio model number CZ624UI, check out this link for more info; http://mnsubaru.com/threads/disabling-changing-the-eq-on-the-2011-head-unit.42771/#post-705031
I am not sure about the NAV units. Others covered several different ones in a thread see if you can find yours in here. http://forums.nasioc.com/forums/showthread.php?t=2317060
