Hey, Tinny sound through surround sound with SP4 connected to TV through HDMI

[Windows Central Question]

Setup:

- Surface Pro 4 (just turned off Dolby Digital on it but haven't tested.)
- Mini DisplayPort to HDMI 4K quality cable to TV
- TV infrared to my Nakamichi NK 6 soundbar/subwoofer setup.

For some reason my surround sound sounds amazing with TV and Xbox on blast. No distortion.

Yet, When I'm playing movies with my SP4 (which I think is connected the best way possible for qualities sake), During certain frequencies my speakers distort. like a tinny sound. not all the time but noticeable when certain people will start talking or certain music.

Hopefully it's because Dolby Digital was enabled. I never use it I think it makes the audio junk...

Thoughts? I'm new to SP4 and SP in general. So any help would be great.

Thanks.