OK, I understand, but I don't think it should be a problem, at least for the way I think a subwoofer should be used.
I would just leave the Eggleston's hooked up as they are (no high pass) and (I assume the Vandy has line level inputs like the Depth) simply connect the preamp outs to the sub(s) line level inputs.
You don't have to put the (single) sub where I did if you can't, but I do feel that the Depth design is probably the least critical of location, the Vandy somewhat less, but it's still down-firing (semi-omnidirectional) and will do OK if it's on a hard surface. I don't think the Grottos are really any different or better than any other single driver mini-sub.
I would just leave the Eggleston's hooked up as they are (no high pass) and (I assume the Vandy has line level inputs like the Depth) simply connect the preamp outs to the sub(s) line level inputs.
You don't have to put the (single) sub where I did if you can't, but I do feel that the Depth design is probably the least critical of location, the Vandy somewhat less, but it's still down-firing (semi-omnidirectional) and will do OK if it's on a hard surface. I don't think the Grottos are really any different or better than any other single driver mini-sub.