Sent my unit for repair here in the UK - I'll endeavour to update this thread with any updates / resolution. My issues are as described in this thread - thanks to everyone contributing with potential fixes. Nothing resolved the fluctuations almost certai. It is a hardware issue
Thank you very much for the info, please keep us updated, so that we know what course of action to take.
So far the company undertaking the repairs have notified me I may need to wait longer because they have to order the parts from ASUS. This would indicate it WAS a hardware issue (likely the right speaker) in my case
Guys.. I've tried everything here with no resolve but, the other day noticed by accident, that when I opened up my laptop to upgrade to 32GB RAM the right hand side speaker was missing one of the orange rubber rings that holds the speaker to the base --- seems its all purpose is to absorb/cushion vibration.
Did some research and found the rubber ring, installed it and seems it has finally WORKED!! so far a couple of days have passed with no issues... Wanted to share asap.. maybe it was a bad batch of notebooks that had that missing piece... who knows... anyway,
I'm super HAPPY! Please share your findings if you have that rubber missing too. Good luck!