I'm a little concerned that you are already thinking about upgrades and would suggest you hold off making any major changes to your system until you've had a bit longer to enjoy your investment.
Personally I think the amp is the best part of your system. Although it has a tendency to get a little hard sounding in more complex passages, the Brio has many fine qualities which would come to the fore so much more with a pair of Rega RS3 speakers, or the outgoing R3s. IMO they are far superior to the B&Ws with a much more natural and balanced sound, although it really depends very much on what music you are listening to and what sort of sound you like.
I think you need to be aware of what it is you like about your system, and what you feel could be improved. Do you want a warmer sound, or more clarity, or a more even tonal balance, or more rhythmic drive??? These are just examples, but focusing in on what you are missing makes it easier to suggest the next step.
If you can't think of anything you are missing significantly at this stage, just enjoy the gear you have until you do come across something.