I replaced the speaker wire in my v2.400 speakers with 16 gauge monster XP soldered to Radio Shack gold plated 1/8" interconnects. I did not replace the female speaker jacks in the speakers. I am using a SB Live sound card. OK, here are my impressions:
If you are expecting a dramatic improvement in sound, you will be disappointed. In fact, you might not even like the new sound of your speakers with the new cables installed, at least this was my immediate impression. After installation, I felt that the sound coming from my speakers has less full and warm. To make sure my observations were correct, I hooked up one speaker with Monster cable and one with the stock wires. I also turned off the sub. Sure enough, the speaker connected with the monster cable sounded thinner and more "distant." The midrange "gap" seemed to be made worse with the wire swap. I had been listening to rock, so I decided to try something different and popped in an opera CD. Here there was a significant difference, this time in favor of the monster cable. Vocals and instruments sounded clearer and more distinct with the upgraded connections. The stock wire made it seems like the performer was behind a curtain, whereas the monster cable sounded more like a live performance.
In the end I decided to stick with the monster interconnects because I felt they produced more detailed and accurate sound. In doing so I sacrificed the fuller midrange of the stock wires, but the new sound was easy to get used to.
Were the sonic benefits worth the $60 for cables and jacks? I would say no. It might, however, be worth it if you need to replace the rear wires with longer ones anyway. I would advice checking out Radio Shack speaker wire, as I can't imagine that the Monster brand would offer a significant performance edge.