K340 bass tuning

This is something I've been playing with for a while, in short, I can change my K340 from sealed to vented so I have more range for tuning the bass. This picture shows how it's done.

Sealed the back with a piece of plastic and taped it in good with electrical tape, but first I put a couple holes in it which I've highlighted with the arrows. How does it work? Well, you can plug one, both, or none of the holes with a small piece of blu-tack, and that'll change how the bass sounds. With the holes open there's more bass but it isn't as tight, you get a bass hump but it doesn't really go any deeper. Close up both holes and the bass gets tight, maybe a bit too tight so it isn't as fun with some of the music I listen to. Normally I close up one hole and leave the other open, the sound is somewhere in between that way.