Help chossing a good speaker. $ 3-5 K

Thanks again. I have narrowed my choice to harbeth vs ATC.

Either will make a great choice and should make you happy.

IMHO, Harbeth's excel at lower volumes with a lovely midrange and warm delicious sound. ATC's prefer to be driven harder as they have a very precise tight punchy bass (sealed box low Q). Depending on your music tastes and how well the room is treated one may work better than the other.

ATC's midrange could easily overpower a small untreated reflective room without carpet - too harsh - so vocals and pleasant sound may favor the Harbeth. However if you want detail in large orchestral classical pieces or big band jazz then ATC will probably carry the day. Horses for courses - remember Harbeth's tend to be used in broadcasting and drama and excel in speech intelligibility and natural non-fatiguing sound whilst ATC's are more like a race horse (rock, movies soundtrack and classical monitoring).

Are your listening preferences more towards going for a nice pleasant enjoyable trot in the countryside or do you want the exhilaration of tearing around the race track? Or put another way, if you like drums with a kick drum and crash that sound like the real deal then ATC will float your boat (for others it may drive them from the room...)

Do you think I will need to crank the ATC's volume up to more than an average of 75-80 db to get them to sound good?

Sincs you have a sub you will be able to compensate for teh lean bass response of ATC at low volume levels. However, I think that ATC 40 will be overkill if used this way. Why pay for something with typically less than 1% THD at very high SPL levels if you only ever need to listen at modest levels. I'd go with Harbeth's for your application.

FWIW - your concern about congestion might be related to your room (most any speakers perform quite well at such modest SPL levels). Unless heavily treated with acoustic panels, a small reflective room will tend to sound congested with most any speaker...you get a "claustrophobic" of cluttered kind of soundfield. So it might not be a speaker issue at all...