[SteveC]

For me, the only setting that works is flat. No treble or bass boost. I would classify myself as an audiophile, with a fairly kick-ass home system. What ever adjustment I use may sound appealing for a song or two but after several hours its always a relief to remove the adjustments and get back to flat.

The most important things I've found related to sound quality are volume and the digital quality of the media I'm playing. Anything less than 256Kbps has to my ear an unacceptable degredation, while the system installed in BMWs needs to play at a certain level to overcome tyre and wind noise, but not so loud that it clips the rather weak kneed amplifier and/or pushes the speaker drivers into distortion.

Whenever you make a change to audio settings, its very typical to like the new settings for a while, but find that surprisingly you prefer the original setting when you switch back a few days later. As a rule, whenever I introduce anything new into my system, I take it out a few days later just to check that I still prefer the system with the 'improvement'.