I have a Raspberry Pi B+ version (single core). The ARM frequency is overclocked to 950 MHz
I also have an IQaudIO I²S DAC HAT mounted. Sometimes, while playing 1080p with 5.1 sound, the video and sound stutters, and the sound disappears for a few seconds till the video keeps stuttering.
After the stuttering smooths out, the sound comes back on after a few seconds of the smoothing out. I've installed OSMC as the OS.