Ubuntu – UE Boom 2 sound quality with laptop is awful

^{Note about the answer here - It appears that Lubuntu comes without Pulseaudio and I assumed Pulse is needed for A2DP to work and that OP would have installed it. It appears not to be the case. The answer below is about a Pulseaudio installation.}

Make sure you've selected the right output sink for the application you're expecting sound from.

Similar to my answer in a similar question, start by installing and starting pavucontrol and check:

• In the Output Devices tab

  • Check the presence of your Bluetooth device. I assume it's listed there stating you see it in another application.
  • Check the obvious settings for that entry.

• In the Configuration tab

  • Check the audio profile. Make sure you've selected A2DP rather than 'headset' or 'off' (unless you want to, really).

• In the Playback tab the application producing sound should be listed.

  • Try to see what output sink is selected and verify it is using your Bluetooth connection.
  • Check the output volume and mute status of this particular audio stream.

maybe it will help you - it helped me:

sudo alsa force-reload

and then:

sudo reboot