99% certainty it isn't related to your adapter. If anything it is going to be
a driver issue for the particular bluetooth device you are connecting or the
device not being properly selected for audio output.
Step 1) DO NOT plug in your bluetooth adapter. Boot up into Trisquel, open a
terminal and type "uname -r" as Magic Banana stated. This will tell you what
kernel version you have installed. I can tell you with 100% certainty that
the adapter works with kernel 4.3 from https://jxself.org/ because that's
what I just tested it with. As a side note, I don't know what kernel
originally shipped with Trisquel 7, but that is likely the kernel version
ThinkPenguin tested the adapter with and so again, it's unlikely the kernel
isn't recognizing the adapter itself. Also, you did note that you updated the
kernel, but you didn't indicate to which one.
Step 2) Type "hciconfig" in the terminal (hciconfig is one of the tools used
for managing/configuring bluetooth). You should receive no output and it will
drop you into the same prompt. Now plug in your adapter, wait a couple
seconds and type "hciconfig" again. You will likely now have some output
indicating the adapter has been recognized (it will have type/rx bytes/tx
bytes/etc).
Step 3) If your adapter isn't recognized, update your kernel. As I said, it
will definitely work with kernel 4.3.
Step 4) Trisquel should automatically have the bluetooth icon appear in
notification bar. Click "set up new device". Connect your speaker as normal,
and you will have the connected jingle from your speaker. At this point the
audio will still play from the built in speakers.
Step 5) You are correct in your assumption that you have to select the
speaker as output (because as far as I'm aware Trisquel doesn't switch the
audio by default). So go into all settings -> sound and select the speaker.
Now as Chris mentioned, the issue is likely the audio profile selected. The
default profile is likely set to "Telephony Duplex (HSP/HFP)" which is NOT
what you want. You want to select the "High Fidelity Playback (A2DP)"
profile.
Step 6) Click the "test speakers" button to the right of where you just
changed the profile. Click the test button and wait a second (you may
actually want to wait a couple seconds and test it more than once because
when I first open it, I have a delay where the speaker only says "left"
instead of "front left" and this could lead someone to believe the speaker
isn't working when in fact it is).
When testing, the device I successfully used was a JBL Flip 3. Best of luck.
