Mine arrived this morning. A doddle to set up although the suggested webpage,
www.chromecast.com/setup didn't seem to be the correct one, I just googled Chromecast Setup and found the webpage easy enough. You plug the power cable into the Chromecast thingy (technical term) and in my case I plugged an old pair of Sennheiser HD595 into the output. Downloaded the Chromecast setup app on an iPad and Nexus 9 and the setup takes 25 seconds or so. You select your home wifi network, stick in the password and then the app asks you to play a test tone.
Warning, take the effing headphones off before pressing 'Test'! Near blew my eardrums out. The volume was set to max by default, I may email Google support and query this. So once that was complete the Chromcast set about downloading a firmware update which took about 20 seconds.
Once that was done the app scans your device, the tablet, for applications that can cast music. It found my BubbleUPnP no problem and offered up a shortcut to open it. I started playing some tracks to hear what it sounded like and was surprised how loud this thing goes with the HD 595. They're only 50 Ohm impedence so the Chromecast could make them go way louder than my ears could cope with. The sound during my short test seemed really good, I heard no issues.
I switched to the HD 650 which have a 300 Ohm impedence and would be harder to drive loud and when I switched I noticed that for the same volume setting they were quieter than the HD595 but this was a volume setting of 20 out of 50. Turning it up, again, this thing could go louder than I could comfortably take. The Chromecast runs warm to the touch but not hot.
I'll try it a bit more tonight and try to do a comparison as best I can with the headphone output of the Hegel H160. The only problem is I have to unplug the 'phones from the Chromecast, plug it into the H160 then switch renderer in BubbleUPnP so it wont be an instant switch between the two.
Ultimately my idea is to buy a dedicated headphone amp/dac, connect the Chromecast with optical and stream my music to my headphones.
But for 15 quid, this must be the bargain of the HiFi/streaming world.
Edit, Curry's are back up to 30 quid but even at that it's still a bargain.