Not the '50 you're asking about, but I did a direct A/B in my main system between the Ref. 30 and Acurus ACT-3 (now available used below $500 as opposed to $1100 or so for the 30.) In 2-channel mode, the Acurus blew the Ref. 30 out of the water and blow dried it. The ACT-3 is not the end-all in 2-channel, either - there are much better (but at the price, it's a very nice unit.) I did not compare with video, but the ACT-3 lacks component, so that's a big demerit against this older unit. That said as well, this is also just about the only Acurus piece I've ever managed to like, having owned several.
I am very very pleased with the Ref. 30 in a HT setup driving an LCD TV via component video, and doing DTS playback of DVDs. I wasn't impressed with the noise floor and lack of air in 2-channel in my main system, which uses 104db efficiency horns (Klipsch La Scalas) with tubes (Rogue M120). The La Scalas will exacerbate noise generated by any component - the Ref. 30 sounded like it was speaking through a layer of gauze compared to the much cheaper ACT-3, which produced much more freq. extension, air and dynamics. Given the setup/matching, I may have been asking for trouble with the B&K, but I can't say based on input impedances etc. as I haven't compared.
The Ref. 30 (and 50), however, have many, many more features than the older ACT-3, which made my choice clear and comfortable - B&K in the viewing setup, ACT-3 in the listening setup.
That said, if I had to listen to 2 channel with the Ref. 30 I own, I'd be looking into setting it up to perform a passthrough (does it even have it? I never even looked that far) to a better 2 channel analog pre-amp.
I hope this input doesn't take anything away from Jafox's response, which is more directly applicable and very well considered. I like my Ref. 30, but chose otherwise for day-to-day 2-channel listening.