>>The other thing to consider is that if you had a mansion (say 20+ rooms), you'd need more than a single set of mains if you were an enthusiast.

Nah... 5 M80s, 2 QS8s and a big stack of Halos

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8