I'm a premium user and its been about two weeks since I've been experiencing very bad quality sound on any song I play. Songs sound muffled, like if I was playing a 96kbps mp3 or even worse. Things I have tried and tested both on WiFi and Mobile connection:

1. Tweaking options for sound quality, was on automatic quality and switched all options up to extreme quality. Didn't solve the issue.
2. Tweaking the normalize volume option. Didn't solve the issue.
3. Downloading tracks on extreme quality. Didn't solve the issue.
4. Deleting cache and saved data from phone and re-open app. Didn't solve the issue.
5. From phone's app manager: force stop app, clear cache, clear data, uninstall, restart phone, reinstall app. Didn't solve the issue.
6. Perform a full clean up on my phone. Didn't solve the issue.
7. I have two phones where I use my account, a Huawei P9 and a Nexus 5, the problem happens on both phones but not on my laptop.
8. I have the Google Play Music app installed on both phones where I have some records that I can also find on Spotify and on Google Play Music sound is great, YouTube audio sounds fine as well. So, it's not hardware issue.

I don't know what else to do, I'm about to do a big trip overseas, 11 hours on a plane and I can't stand thinking I'm gonna have to listen to really crappy music quality for all this time. Please help me!

Device and operating system:

• Huawei P9 running on Android 6.0
• Google Nexus 5 running Android 6.0.1

Type of Spotify account you have: Premium

The app version of Spotify you’re using: 

8.4.18.743 armV7 on both devices.

Thanks in advances for your help!