SteveR750:
Having got divorced last year I live in a semi with walls that have the sonic opacity of air after years of a nice shiny new large detached house where the limiting factor really was the current output of my NAD amps over the years. I did live in a newly built semi and that wasn;t much better than the 1930s place I'm in now, but unless you have accommodating or deaf neighbours a good system will rarely be used to its potential, and it really makes no difference where you put the speakers.
Why most semis are built with their lounges adjacent and entrance hallways separated I do not know, unless its felt that having your entrance door as far as possible from your neighbours is a *good thing*. I have been looking for a place to move to for a while where the lounge / living areas are on the external walls of the semi block, so at least there is a an extra layer of cardboard isolation....
So true - we've been in our 70s semi for 25 years now, and we still love it - but that's partly because I was fairly persistent about finding one with outside lounges. I'm rather obsessive about noise from neighbours (hey, I'm a fully paid up Grumpy Old Git), but equally about not causing a similar nuisance to others. Having concrete floors as well means that, touch wood, we've had no problems or complaints in all that time. I think though that the day is coming soon for a move to a nice detached, and really being able to unleash the system!