This reply is probaly a bit late for you, since you have already purchased the unit. I have purchased a couple of 507's last year after doing tons of research and reading posting on this site. The first until I purchased was from a dealer that was dropping the BK line and I was able to purchased for $2,400, no doubt, a great price. I took it home and was inspired, the layout, connections, shell, all quality. However, my inspiration was repressed after listening to pops, humming and other unexplained noise from the unit. I took it back to the retailer and was refunded the full $2,400 - I thought I purchased a bad unit.
Since I really wanted to like to unit for the sonic values, I decided to give BK another chance, so I took my original reciept (from the 1st purchase) the local tweeter and purchased a second unit for $2,400. Another great price.
After lugging the unit up to the media room (it's heavy), I reconnected it the speakers, DVD, etc. Much to my dismay, I got the same humms, pops, etc from this unit. I spoke with BK and they thought it was bad power at my house until I informed then it was a new house and the electrical was earth grounded and I have a Richard Gray conditioner.
I was also not impressed with the 2-channel ability of the unit. So, I took it to a local high-end shop and compared it to a Rotel receiver. IMO and others, the Rotel sounded better, it was more detailed and controlled the low-end much better.
Instead of opting for another reciever, I purchased the rsp1066/1075 combo, did more comparsions at home. IMO, the Rotel combo at $2,400 MSRP beat the BK at $3,500 MSRP hands-down. The final decision is yours, I really wanted the BK and really wanted to love the sound quality, but my ears were the true test. I suggest you do the same. Listen to opinions of others, but in the end, it's your money that pays for the unit.