@mitu Thanks for getting back to me...
I think the power supply should be fine? I just left the machine running (attract mode goes into demo mode through various games) for an hour and the sound was still running fine! The USB adaptor for sound is just one of these:
https://www.amazon.co.uk/gp/product/B07MNRRT84/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
I use this as it was a solution for hissing audio - found a solution on these forums, instead of running my amplifier from the Pi's audio jack it now comes out Pi's USB via the adaptor, the setup alterations I made are here:
solution for sound.png
I also don't get any voltage warnings or any warnings during gameplay.
Hope that was everything you needed?
Cheers