I recently upgraded to Nougat and experienced sound issues using an OTG cable and my Sound Blaster E3 DAC. The sound was basically panned hard to the left, slower than normal, and there was some distortion.
I realized that ES File Explorer was activating each time I plugged the E3 in. The simple fix was to remove ES File Explorer. That being said, I'll probably experiment with its settings as it's a useful utility.