My wife and entire family now think I'm nuts. So I went to the Apple Store yesterday and spent 30 min showing them the text message issue. Mine is intermittent, so it took about 5-6 text messages before the distortion appeared. Genius guy pulled his out and guess what? He's was exactly like that too. Another 2 genius guys came and they both had it as well. Of course they said that the issue didn't bother them but if I wanted a new one, they would be happy to replace. I declined and when I got home decided to try out my wife's again. First, my wife's 6s never exhibited distortion with the text messages and all I did since the last time I played with hers was update it to 9.1 beta 5. to my surprise, hers also now has the distortion! I called my uncle up in San Fran and asked him to try and his also has the distortion. So now I am sitting at 7/7 (1 of my friends also has a 6s) for distortion on the 6s with the message sound. By the way it disappears for a bit if you hit the audio message button beside the text entry line, weird! But unfortunately comes back. Only difference is that I'm the only one that seems to care.
NOw on to the daft punk song. My wife's 6s and mine have slight disortion as well as my uncles 6s. My mother in-laws 6 plus also has it as well as my father and father in-laws 6. Mom doesn't have an iPhone:) Now you know why they think I'm nuts! So all have it and if you want to really hear distortion in a song play time lapse by thefatrat from 1:40-2min. Once again all 6s and 6 listed above have this distortion.
SO, I'm not exchanging mine because I'm still not sure what the problem is. When my wife's had no issue, I noticed that it could not get as loud as mine. Now after the update it is not distinguishable from mine in loudness and does have it. Is it software, not sure, is it hardware, not sure, especially after what happened to my wife's phone. Only time will tell and hopefully my family across North America forgives me for asking them to do this 🙂
Best of luck for everyone.