i would like a customizable graphic equalizer. or even preset ones will do.
The N900 doesn't have a HW equalizer so all sound spectrum modifications need to be done the hard way, by the CPU. Look at what the software based internal speaker protection impact is on pulseaudio CPU utilization. It's a pity the DSP isn't better used for this. But there is an audio player already having an build-in 7 band equalizer, Symfonie. Maybe that one is what you want ?