Well, I see four options.
The first and most obvious is to stick with what you know. I found it hard to find prices for B&K receivers, the ones I found were over double your budget. Perhaps that have a suitable unit in your price range.
Option two would be to go with another expensive line, like NAD. I have an NAD T762 which has been a solid, good sounding performer the last 10 years. Their T 765 is in your price range.
I wonder if there is a true discernable quality/performance difference with the more esoteric brands like B&K and NAD. I used to think so, but now I'm not so sure. I wonder if the price difference has more to do with having to spread similar R&D costs over smaller numbers of units sold. That leads me to my next option.
Buy a higher end receiver from a mainstream brand. Pioneer, Denon, Onkyo and others offer some pretty beefy receivers in the 2k range. I just replaced the NAD in my home theater with an Onkyo TX-NR808 which runs less than $700. I replaced the NAD for the same reasons you're looking to upgrade. So far I've been extremely pleased, the SQ is actually better, especially after using Audyssey to EQ the room.
The last option would be to buy a pre-amp and amp combo. You could get an Onkyo PR
-SC5508 and and Emotiva 5 or 7 channel amp. If I could spend in the $2k+ range, this is what I'd do.