I’m far from an expert, but after looking at the specs on your B&W speakers and Yamaha receiver, I would think that you’d benefit more from a better amplifier than a DAC.
The Cambridge Audio integrated lists for $1,500. It looks to have preouts that would allow for a power amplifier upgrade in the future (Good). It’s rated at 4 ohms (Good). Is Class AB (good).
The Yamaha integrated lists for $900. It looks to have preouts (good). It’s only rated for 6 ohms that should work with your speakers, but a 4 ohm rating is a strong indicator of a better amplifier. Looks to have a decent DAC (good).
The Rotel integrated lists for $1,600. It looks to have preouts (good). It is rated for 4 ohms (good). Looks to have a great DAC feature set (good).
I don’t have experience with any of these components, but have had a couple of Cambridge Audio amplifiers briefly and really didn’t like the sound. It was "grainy" to my ears. I looked for another Yamaha a little farther up the line, but the next jump is significant. I suspect the Yamaha would be a fairly high value item. Out of these options, I’d probably go with the Rotel. You might also look at a Marantz PM8006 that retails for $1,500. I tend to think that you can sometimes get a higher value from a bigger company that has buying power and manufacturing capability.
The primary features that I’d look for is preouts and 4 ohm capability. Specs are not everything, but I consider these two be reasonable indicators of a decent amplifier. Hope this helps.
Update: I just realized that the Marantz doesn't have a built-in DAC, so not quite the same as what you're looking at.