Yes I too noticed this frequently on my iPhone XS. At first I thought it was a specific song, but it happens randomly. Sometimes I have the feeling it is more frequent than other times...

I have the exact same thing and it is indeed much more notable with songs that have a lot of high frequency/treble. The in-ears are even set to “sound quality priority”. There are a variety of bugs which I hope Sony will fix soon...

I was wondering if you can you use the in-line microphone and controls with the Nexus Aqua. Or even any of these external DACs? I found one Kickstarter project that is about to release soon: the Cobble Micro Audio Amplifier which cost 59 USD through Kickstarter.