Difficult, because I believe some of that forwardness comes from the 685s. So much so that I sold mine because I found them very tiring to listen to over long periods. Very capable but....
I'm not sure how much you can improve on your NAD for that budget. On the second hand market you might be able to get a Marantz PM7001 or PM7002 if you are lucky, and either would be a great buy although I'm not sure how well they would partner with the B&Ws.