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I have a 5.1 JVC receiver and of course a DVD player. I have two Poineer speakers (which sound pretty good). What I would need is two extra shelf speakers, a centre speaker and a subwoofer.
Passive speakers it is then - anything else is a waste of money for unecessary amplifiers and circuitry.
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For shelf speakers I've been looking at the Sony SS LA 300, because I like the way they look
On a related note: Sony likes to call these and a few other speakers 'Extended Definition'. Are there any factual differences between ED and regular sony speakers, except for the price?
I have never heard these particular speakers. I would assume that "extended definition" is probably a marketing differentiation betwen the cheap plastic single-driver + "sub" bundle systems Sony sells millions of and multidriver speakers like those you linked.
I cannot stress strongly enough the necessity of auditioning speakers before you purchase them; what sounds good to some (horn loaded tweeters, dipole radiating speakers) can sound downright irritating to others.
With your budget you should invest in a decent powered subwoofer (a good 10" in the 150W (actual - not multimedia rated) range should be quite feasible), and spend the rest on shelf satellites. Also, if you intend to keep your Pioneer front channel speakers, you may wish to try to find sats and a center that 'voice match' the Pioneer's.
For passive speakers I like Definitive, Pinnacle, Paradigm, PSB, MB Quart, NHT, B&W & KEF.
The Paradigm Micro and Atom in particular, can be found for extremely reasonable prices used on-line. In terms of output quality they are far in excess of any multimedia satellite speakers bar none, and are quite likely significantly better than the Sony's you linked.