What you want is a player with onboard decoding and multichannel analog output. There are a few options.
Panasonic: the BD50 (only 5.1 analog out), BD55, or whatever the BD55's successor is (model number escapes me). The BD50 and BD55 are a little pricey now, if you can get them, and the BD55's successor is probably not shipping yet - it was just announced at CES a week or so ago.
Sony: the S550.
Samsung: the 2550 I think is the model number for what you're looking for, although Samsung's players have been rather borderline on quality (not necessarily bad, but a bit more of a risk than Panasonic or Sony).
OPPO: the BDP-83 is still in beta testing, with a possible Early Adopter Program on the horizon. If you want something today, it's not the right choice. It's coming, though.
Of these, I'd lean toward the BD55 or S550 if you want something today (and the S550 can probably be had for the best price, as apparently the deals on the BD55 dried up as soon as it was discontinued during CES). If you are in a position to wait a bit and can handle something around $600 (estimated price, but nothing official yet), the BDP-83 will offer better DVD scaling performance, more features (DVD-Audio and SACD), and excellent quality once it arrives. Details on performance will arrive once the EAP starts (we are assuming that it will happen, although nothing's definite on that yet), but until then I will just say that both Peter Tribeman and I have been very impressed with our beta samples and it's what I'm recommending to a couple 990 owners I know locally as a Blu-ray solution for them.