Harbeth 30.1 or 40.1


I would like to get a pair of Harbeth, and wondering if 30.1 or 40.1 is better.  My room size is about 18’ x 16’.  I currently have a pair of Spatial Audio X5 with large 12” mid range driver.  I would say I listen in low to low-medium volume for Jazz and vocals.  Is 40.1 too big for my area?  I am afraid if I am not listening to what it is supposed to sound like if I don’t turn up the volume.

however, if I buy the 30.1, is that I should get a pair of sub?  Versus for 40.1, I assumed I don’t need subs?
gte357s
I don't think you would need a sub with either. The 40's will blow more air which might be not more but much more then you would want. With the Harbeth what you get is a special midrange that in itself is very satisfying. Hook em up to a sweet sounding amp, tubes are nice and you should be happy. For me I would go with the 30's. less room resonance fewer acoustical treatments tighter sound....just me. 
To me they are very different speakers I like them both but the 30.1 is a great small monitor speaker. The 40.1 though stand mounted is totally full range you definitely wouldn't need a sub with it. With 30.1's you may not need a sub either unless you're a bass freak. Do you have a chance to audition them and see which you prefer?
I think the 40.1 might be too big for your room-they have to be out from the walls quite a bit.  Spatial speakers are really good.  What is wrong with yours?