Bryston and Mac are like apples and oranges. What amp have you been using, what improvements and sound characteristics are you looking for, what’s your budget, and are you looking for new or used? The more info you give here the better recommendations you’ll get.
Maybe buying a different amp
The amp I've been using is going on a little over 20 years old and thinking about a different one and have my eye on possibly a Mcintosh MC352 or a Bryston 4B3 and both are around the same price. They would driving a pair of PMC PB1i and have read that PMC and Bryston have a sort of synergy for some reason.
Any comments please?