I'm having a weird problem which I couldn't resolve. I have a rMBP 13" early 2015 connected to a 4K tv through TB2 port with Club3D Mini Displayport 1.2 to HDMI 2.0 adapter and HDMI 2.0 cable and I can achieve 4K resolution with 60Hz. Only problem is that I can't get sound in this settings but I can get sound when I switch it to 4K 30Hz or another resolution. I used SwitchResX to create custom resolution as otherwise it's not possible to get 4K 60Hz. The bandwidth of TB2 is enough so I don't know what might be the problem. I checked sound settings and Audio Midi setup so there is not much to do there. Any thoughts?