/**Article updated on 19 Jan 2013*/
Here is the portable version of v1.1.15 with some added stuff. No installation required, but may need admin privilege.
2.) Subwoofer physical inspection
Eliminate any physical barrier that stops the subwoofer from working harder. The Altec Lansing ADA885 was designed to have its heatsink protruding the reflex port. This heatsink blocks some air coming out of the subwoofer and therefore gives this annoying sound when cranked. I replaced the heatsink with compatible one which just cost 3 bucks on ebay and problem solved!
Other subwoofer like Edifier R501 and Cambridge Soundworks 550 came with protective filter or grill that prevent foreign object to enter the subwoofer chamber. I simply pull of the protective net or break the port grill so it doesn't block anything coming out of the port.
3.) Find your subwoofer sweet spot
Play around with your subwoofer location to check if the sub sounds better when it is facing the wall or placed nearer to the corner of the room. Every rooms have different sound characteristic, therefore there is no universal trick here.
Tilting the subwoofer may also help, especially if the subwoofer is downfiring ones. The Megaworks 550 has a downfiring sub and it causes the desk above it to rattle each time the bass hits. So I tilted the subwoofer -90 degrees and attach some rubber feet. Result? 'muddy' bass is less than before, and desk rattling is significantly minimized. (See Picture 9-10)
4.) DO NOT MAX the bass knob
Upon investigation, most bass knob only act as either attenuation knob or fixed equalizer knob. Maxing this knob doesn't help you get more optimal bass. Find out which position gives you the smoothest bass. And then foobar2000 will take it from there.
5.) Test your subwoofer frequencies response
Listen from 100Hz to 30Hz without changing your volume level. Then take note which frequencies you wanted more or less. If your subwoofer is smaller than 6.5" you can stop at 40Hz instead.