How much do they weigh? Are they the same shape as the HT-1? Do you mind drilling holes in the back?
I don't have any sealed HT1's at the moment and, therefore, do not know the weight. They are 9" wide, 15" tall and 15" deep. I would gues they weigh 35 pounds. So the BT-77 will not work.
As for the BT-77 with SongSurrounds, I have a pair of very similar MBOW1's in my shop in a high vibration area and they have been hanging there for about 4 years - no problem. We have quite a few other customers who use this clamp as well and seem to be very happy with it.
- Jim