It certainly helps as it keeps the tonal balance the same across all speakers. It's not essential though. Quite often people piece together speakers from various manufacturers but getting the balance is more difficult.
If you have speakers from one manufacturer it also looks better but this is secondary to the way they sound. If you are buying a surround sound set up from scratch then I would get package or sets of speakers from the same manufacturer. If you are adding to your existing hi-fi then you may wish to buy new speakers from a different manufacturer.
Thanks Orinj for the advice i have jamo front speakers and some cheap rears that i got from argos just to do the job that I'd like to upgrade.
If anyone could recommend any i'd be grateful, also need a centre speaker but my local dealer is selling a jamo half price for £50 so might purchase that.
it's not so much the same make, as the same kind of sound.......especially across the front three speakers (front left, centre and front right)......so for instance, using a pair of speakers with rubbery type mid/bass drivers for front left and right with a centre speaker that has a metal based driver will probably not sound too fantastic....
but using a centre speaker with a similar form of driver will go a long way to sounding more uniform and less obvious that its a separate speaker.....but yes, if you stick with the speakers from the exact same range then they should sound a lot better, altho not so much if they are crap speakers to begin with..lol
Jamo are usually nicely put together for the money, i used to own a pair of the D series, D110's, not the last word in HiFi quality, but they had a beautiful bounce to them with dance music...heh...