I think you have your chain out of order.

First, I would just ditch the phantom power box and use the phantom power on your mixer. Unless you really like the separate box for some reason. So plug your mic into your mixer's mic XLR input, switch the phantom power on the mixer, send that channel out through an aux send (I guess, since you don't have direct outs on that mixer), aux send to your DBX's input, and DBX output to soundcard input.

You might have to get some different cables or adapters to match everything up, but this should be a much purer signal. There's a few other ways to do this I'm sure someone will recommend.
Make sure you don't have your gain staging goofed up; don't overload the compressor with too much gain from the mixer, or don't send a low level signal out of the mixer and boost it a ton with the compressor.

PS: If you are unsure of what compressor settings work best on your signal, it might be wise to just leave it out of the chain for now and you could compress later in the software or something.

Lay off the compressor for now. If you want to mess with it much, just wait until you're in mix phase.

Also, a lot of the "muffled" sound is probably the behringer mic going through a behringer mixer. There's other mics in a similar price range that will give you better results. You don't have to buy a Neumann but you might want to upgrade just a little.