PMC TLE1 vs Velodyne DD-15 vs JL Audio f113

That's a tough choice. All of them are good subwoofers. The PMC TLE1 is the lesser known compared to the other two. I have this sub matched to my PMC main speakers. If your main speakers are not PMC, Velodyne and JL Audio may be a better choice. I have not done any comparison between these three subwoofers but the dual 6.5" woofers of the TLE1 go down flat to 22Hz and trounce my Dali SWA-12 with single 12" woofer.

I agree with Ryder - if you have PMC then you need to consider that it is TL design in the bass (not sure what that does to phase - so it makes sense to go with PMC designed matching sub to help avoid potential phase issues). JL audio seems to be best value for great performance.