Set equalizer settings that works for all sounds from any programs? Can we set equalizer sound settings in some program, then go to any other program that produces sound knowing that those settings would apply?  For example, set it so that bass is enhanced across the board.
DSP Manager (root only) is an app that's incorporated into a number of custom ROMs.  I have it in my CyanogenMod but I know it's available in others or as a stand alone (that you have to flash over your current ROM) depending on your device.  Search XDA for "DSP Manager" in relation to your specific device as there are numerous device specific threads and downloads.