To bridge or not to bridge....

First of all how hard are you driving the system? Do you turn you volume above 3 o'clock?
Did you check if your speakers can handle 600W/ch(I believe that bridged Brystons 4b-st through such wattage in 4Ohm or even more)?

Do you mean that your 4B-st were clipping??? With what speakers???

Dedicated monoblocks will definitely do the job better than bridged amplifier.
If you somewhay sacrifice quantity over the quality you won't go too far away towards higher budjet over getting another 4B-st.
For example most-likely if you get VTL MB225 you will stay with the same power and you won't be red-ligtning.

Richard,
First we've got to make sure that the author's speakers are bi-wirable. Second we need to know what kind of speakers are we talking about that even Bryston 4b-st doesn't have enough current to swing a woofer(is it some 1000W woofer??)

7b-st as suggested by Ozzfly is basically the same thing as 4b-st but made as a pure monoblock and certainly sounds better than bridged pair of 4b-st. Thus in the case with Bryston and with most brands it's much better to go for dedicated monoblocks instead of using bridged pair.

And at last the question:

If I have amp 1W/ch and I want to use a bridged pair will I add 3dB to the volume?
I guess not! The whole different issue when you double 250W/ch or 200W/ch isn't it?

Yep, the truth is there that your unit needs to be checked.
Good to have 20yrs transferable warranty though!