I've had this issue since around the time Lollipop came out. Music intermittently drops out (or stutters) when listening over any Bluetooth device (never otherwise). Turns out the problem isn't specific to this phone (or Samsungs in general), but I thought the information below might be helpful since we've discussed the issue here before, and the S5 seems to be particularly vulnerable to it.
Found an AOSP bug report thread with hundreds of similar complaints that date back almost 2 years, across many brands of phone, including Nexus phones.
Only workaround that seems to consistently help is to force the screen to stay on (which explains why I never experience it when running Waze).
Amazing to me that a problem this serious has gone unresolved for so long
If you've experienced this, please "star" the bug report (top left, next to the Issue number).
"Bluetooth streaming audio dropouts when screen is off, Android 4.4.4"
Issue 95294 - android - Bluetooth streaming audio dropouts when screen is off, Android 4.4.4 - Android Open Source Project - Issue Tracker - Google Project Hosting
Found an AOSP bug report thread with hundreds of similar complaints that date back almost 2 years, across many brands of phone, including Nexus phones.
Only workaround that seems to consistently help is to force the screen to stay on (which explains why I never experience it when running Waze).
Amazing to me that a problem this serious has gone unresolved for so long
If you've experienced this, please "star" the bug report (top left, next to the Issue number).
"Bluetooth streaming audio dropouts when screen is off, Android 4.4.4"
Issue 95294 - android - Bluetooth streaming audio dropouts when screen is off, Android 4.4.4 - Android Open Source Project - Issue Tracker - Google Project Hosting