FINAL RANT:

I really don't like the changes going on right now. It's like people with more money than brains have taken over or something...

For example: LightDM devs decided [Seat Defaults] is just too much plain English for us to handle so they changed the config file format to [Seat:*] which is unintelligible Egyptian hieroglyphics. Same over-educated rich brats decided that eth0 and wlan0 made too much sense, so now we need device names like enp2s0f0 and wlp3s0 -- I'm not really sure which one is wired and which one is wireless but I thank Jesus they didn't go full-blown stoopid (that's the new spelling) and give them UUIDs for names -- In any case, 30 megs of international language support was just too much space to waste on today's multi-gigabyte drives so locales only does one language by default now and overwrites all your previous language settings. Those are just a few examples, I could write several pages more on all the stoopid changes.

In short, I like 8 with 9 backports better and have no interest in 9 at this time. If you're a glutton for punishment, however, you CAN switch the 9-11 edition to stretch (testing repo) by first doing a sudo apt upgrade on a clean 9-11 image (see previous blog post), then sudo apt-get clean to purge 8.4 packages out before finally changing the first line in /etc/apt/sources.list to:

deb http://ftp.debian.org/debian stretch main contrib non-free

The next time to you apt update cache will be populated with Debian 9 testing packages and next time you do sudo apt full-upgrade you'll get XFCE 3.12 and everything else in 9 that's not in backports. Good luck...

FINAL ADVICE:

Simply put, PulseAudio just doesn't work right with the analog snd-bcm2835 driver you'll find in /etc/modules-load.d/modules.conf but it's the best thing since sliced bread when it comes to Bluetooth audio. I resolved this issue by muting (turning volume to 0 on panel applet) the analog and only using Bluetooth. You could also simply remove the driver. If you need the audio port on the side of your Pi 2 to work correctly stay with the 9-11 edition which only uses ALSA. It's my understanding PulseAudio does some fancy resource saving by making the daemon go to sleep and wake up and that's what the old driver doesn't like.

I currently have over 16 gigs of music on my Pi 2 (my cell phone choked after 12 gigs) and use it as my main MP3 player with a Waveshare touchscreen. I also use Bluetooth for almost all my small file transfers to/from my laptop and phone. It's just so much easier without all the security garbage that inhibits freedom. After pairing I just send the file and click the accept button on the other end. That's it, no Internet connection, no Google account, no password and no TSA naked body scans required. For larger files and backup imaging, a USB 3.0 microSD card reader comes in handy.

How to upgrade and debug broken packages

The 9-11 version is very stable but sometimes problems pop up with backports as happened recently with the Audacious package. To start, query the package database to see what versions are in the configured repositories:
apt-cache show audacious

Looks like the www.deb-multimedia.org version is 3.6 so we need to delete the most recent:
sudo apt remove audacious

Then get the right one:
sudo apt install libaudcore3=3.6.1-dmo1 audacious=3.6.1-dmo1

And finally lock the package so we can upgrade in the future without problems:
sudo apt-mark hold audacious
sudo apt update
sudo apt upgrade

For the 9-11 version you should:
sudo apt-mark hold locales
sudo apt update
sudo apt upgrade

Periodically you should also:
sudo apt-get autoremove
sudo apt-get clean
to free space on your SD card.

NOTE: new users only need to do the commands in red to a "clean" image.