[lubuntu] No sound in Lubuntu 16.04

Hi,

I'm testing Lubuntu 16.04 from a USB stick on my Toshiba laptop, and there is no sound output from speakers or headphones. The audio hardware is a Realtek ALC269VB... although Ubuntu and Ubuntu Mate both play sound on this machine without any trouble, in Lubuntu, the laptop's volume keys do nothing, and there's no tray icon to control volume/mute.

I've tried ruing alsamixer, tuing up all output faders and disabling auto-mute... still nothing. Any idea what to try?

Thanks in advance!

-Mark