Indeed, Peter. It was rather interesting (and also quite funny) when I lugged the Lockwoods once down to Scalford, and demonstrated them in a room about four times larger than mine...
First of all, during the set up stage, where we were playing around with speaker positioning, it became blatantly clear, fairly early on, that the Lockies sounded best when placed up close to the back wall, and also slightly toed-into the central listening position (exactly the way I have them at home).
Consequently, that's where they were put, despite having umpteen other options, which would've utilised the much bigger area available. However, every time we tried to use them in free space, the bass boomed like a bastard, so that was a no-no - and also it became equally clear, that the best sound was obtained by sitting approximately the same distance away from the speakers, as I do at home...
Secondly, the punters attending the show, who came into our room, nine times out of ten, if they could get a space (and had a chance to compare the sound in different parts of the room), sat in the second or third row of seats, which were placed approximately the same distance from the speakers as I sit at home, as that was, quite clearly, where they sounded best!
Conclusion: a complete waste of time using big Tannoy DCs in a large room, as you'll only end up listening near-field, because that's where they work/sound best, so having a big room completely defeats the purpose!
Marco.