Thank you for the reply!
I do have speaker environment set as 2-speakers, the output mode set to Dolby Digital Compatible Downmix, and in the advanced tab enabled the LFE option. While this has reduced the subwoofer volume by a bit, I still find it too loud most of the time.
I guess I'm asking too much from downmixing a 5.1 to a 2.1 stream, but I was sort of thinking along the lines of an external application that automatically remixes the 5.1 channel sound to 2.1 channel sound. Probably doesn't exist.
Thank you though!