i personally would look at the below points before buying any hifi gear.
1.) "The heavier the better" is good when choosing amps/DAC/cd player. This has the effect of greatly reducing any and all vibration that could adversely affect audio quality. The construction of the gear with heavy chassis and bullet proof body doesn't allow any external vibrations like floor noise and the music being played itself pass thorough the body and hit the components. You can find a lot of resources on this topic in internet.
2.) The company and the location where it is manufactured. i avoid "Made in China", for the simple reason that it reflects the company's mind set of building a product using cheap labour and earning high revenues. Even though a big brand designs a product elsewhere and manufactures in china, the components are still procured internally. That said, i don't say everything made in china is bad, but i avoid "china".
I simply choose products made in Japan, Germany, UK , US ( not in that order of choice though).
For buying a DAC, i suggest don't look at just the DAC chip being used. The DAC chip manufacturers sell their chips to OEM manufacturers who design and implement these DAC chips in their product. Look out for manufacturers who pay attention to the analog stage, power stage, DAC stage, output stage, jitter, master clock used.... etc., and overall how they have implemented the chip in their DAC itself. For example PS audio, Musical fidelity, Metrum acoustics, make great DACs.
Remember two manufactures taking the same dac chip and implementing them in their DACs will sound totally different. one may sound better.
Its really not what DAC chipset that is being used in the DAC that matters, but how its implemented.
Avoid head phone DACs and anything else merged into the DAC apart from its job of a DAC.
Finally You need to choose a DAC thats matches your other equipments in the chain and the speaker, maintaining synergy, which is more important than choosing the best DAC from the best company.
As far as cambridge audio CXN is concerned, just connect with your local dealer and find out if he can provide you a demo. A demo at your place with your room acoustics and your gear and not in their place.
CXN uses a dual wolfson dac chipset, and its a 24 bit dac, and those specs cannot determine its quality of music. You need to personally audition it to like it or hate it
I would consider Yamaha's streamer which is decently built and costs less, again i would use this for only streaming and not for its DAC. i would feed the digital out of it to a good DAC.
I am not a fan of streaming at all, and still prefer SACD player and CD/SACD as the source, & of course Vinyl.
even if its the same content on both streaming or a stand alone player, jitter and noise are considerably low in a stand alone player.
I understand big brands cost huge, but you still have the option of picking up a great used DAC from a credible source.
There are lots of things to discuss on this topic and its difficult to articulate everything here in one go.