To bridge or not to bridge....

I have a Bryston 4B ST and lately have been red lighting.
So I want to bump up my power.
What is the best way to go?
Add another 4B St..bridged?
Buy separate mono blocks..it doesn't have to be Bryston.
What is the difference,if any, with mono blocks over a pair of bridged 4B ST?
Or stay with a single amp with more power?
I have always found this to be very confusing.
The cheaper way to go would be another 4B ST.
I will update my speakers later.
Any info/direction would be greatly appeciated.