Think you could possibly be right on the overkill (if there is such a thing :p), it's hard to give the correct dimensions as like I say its in a roof space but it has a 5 metre front to back by 8 metre wide floor. However the vertical space is in the triangular shape of the roof with it's highest point being aprox 2.7m so most of the 8 metre wide floor space is tucked away in the eves so really theres more like 5m x 4m of usable floor space that you can actually stand up in if that makes any make sense!\n\n\n\n\nAh man I haven't even had a chance to start looking into those yet, the Mrs keeps making me work on the stupid house renovations when all I want to do is plan my HT out but yes I was definately thinking beefy!;) Never built a sub in my life so correct me if I'm wrong but thinking I could possibly build the cabinets with a sloped back (if I can figure out the maths!) so the back of them could fit into the wasted empty floor space in the eves. I was also thinking I could also fit some pretty thick acoustic absorbers in these wasted spaces, without going overboard on them obviously.\n\nYou can build sub cabinet with sloped backs, it won't hinder performance. You just need to make sure to compensate so that the internal volume of the enclosure remains the same.