M&K MX 5000 THX MkII vs Velodyne HGS-18

They are both great subs but if you are 70% HT then definately get the HGS-18. It has tons of extension and if you set the crossover low enough it works very well for music.

scrap both of them and go with a pair of HSU TN1220's with the 500watt amp, get better performance and pocket some cash to boot.

Both are excellent subwoofers. I have had both in my system. In my opinion the M&K sounds a little more accurate on movie soundtracks. I prefer the velodyne on 2-channel music. I currently own the M&K 5000 MKII