Below what frequency does sound lose its directionality? A bookshelf that only does upto 50hz with a sub is no-no for sure. One will lose spatial cues in the critical low mids. Moreover I suspect while a sub might provide the low frequencies, a budget BS + sub will not produce deep rich tones even though you may cover a larger frequency range. If someone can convince me otherwise I will be willing to invest in a sub
This has been an discussion I remember we have had before on this forum. I have listened to (and continue listening to) a large number of BS and FS, and frankly I lean more towards FS, particularly for music. The sound stage a pair of FS can create simply because of the amount of air they push can never be matched by a BS. But again this depends upon the type of music you listen to. If you listen to heavy orchestral music with a large number of instruments, an FS has an edge over a BS. A well designed FS can cover whatever advantage a BS has for mid and high frequencies.
I was privy to this at Viren Bakshi's place where I was surprised by the volume and sound stage created by his single driver speakers. Viren explained he has designed and created the speakers to create and expel a large amount of air to create larger and deeper sound stage. The way his speakers rendered the 50 odd man orchestra in 'A Faint Flutter' from Raaga Symphony was impressive, to say the least.
Movies are a different matter altogether. As Vortex and Moser have said, a pair of good bookshelves backed by a good sub will do wonders. I have realised that, for movies, the most important channel is the centre channel. I would go in for as large a centre channel speakers as possible. Even a pair of large FS as fronts will not be able to compensate for a weak centre channel. Bulk of the data is sent to the centre channel and that is where the stress on speaker size and quality has to be focussed.
Cheers
