The HGS models(10, 12, 15, 18) were the flagship line in the late 90's through early 2000's. Even today, without built in EQ, the HGS models can hold there own with many quality subwoofers of today both musically and for HT.
Thanks Bill. I seem to recall this fact too when I acquired my SPL1000 - the HGS just being a bit over-budget at the time. Since then, I've noticed many HGS owners discussing issues w/ the internal amp blowing, assuming normal use. I've never had a problem w/ my SPL, though it is a tad noisy w/ low-level hiss.
I have the Velodyne SPL 1500 and I find it an enjoyable sub for HT or music. I'm using it for my music system now as I my desire for HT is dwindling. I got the SPL 1500 almost new from a reputable online e-tailer at a really good price so I jumped on it. Years ago I spoke to an engineer at Velodyne and he said that the older HGS series of subs is basically the same as the DD line without the eq and remote.
I have had a velodyne HGS 18 for years and love it for 2 channel and HT. The amp went out after several years.Took it to Velodyne factory and they replaced the amp with a rebuilt amp in less than a hour. It did not cost a lot for the replacement. I have talked to velodyne several times and the support is great.