Went as far as uninstalling the factory driver, installing the driver listed on this forum, and hunting around in the BIOS for the Audio DSP UAA setting (with no success). Equaliser is still not available on my V5 EzBook 3 Pro (calling it a V5 as it’s the batch manufactured after the V4). Not sure why the later versions do not allow equalisation but there it is.
I did notice that the default Microsoft driver will allow “Bass Boost”, but I tried that on a Bluetooth speaker and it does not result in louder amplification.