Yeah true, but I preffered my set-up with comps in the front and coax in the rears, had the rears turned down a bit but it gave a fuller sound which I liked.
Sent from the golf club...
They definitely add depth, but for improving the sound quality first he'll need components.
Saving the pennies for a decent 4/5 channel amp after buying the components would be the best move for me, then a sub then, if you really must, a decent set of coaxials.
The trick is to buy all speakers of a similar level so that they all perform the same, nowt worse than having unbalanced speakers.