Exactly...unless you have a clean and properly grounded socket, cables, every device in the chain actually....which should be hard or impossible, to achieve proper grounding in a car ?
Out of curiousity I tested some other headphones while charging:
- AKG K701 : No buzz/humm whatsoever...totally clean while charging. It's my least sensitive headphone...needs alot of current.
- Blessing 2 :No humm whatsoever , even on unbalanced . And this one has almost same sensitivy as the fh3, I think slightly more
- Ananda, balanced : I hear about 0.5% of the charging humm of the fh3 , you have to listen really hard in a quiet room. Can't hear it while playing music.
- Still kind of a pity, since it's my favourite headphone by far and I thought I had found the perfect combination of headphones and great bt amp. Going to try a different cable and a different power socket. Btw the Ananda is really easy to drive almost like an IEM.
- Fiio FH3 : well you heard the full story : I get so much humm you can't really listen while on a power socket . And Qudelix was explicitly promoting that functionality, using it from a power socket won't wear the battery down, increasing the lifetime by only powering through usb and not touching the battery as soon as it's fully charged.
- Sennheiser HD660S : Highest impendance of the lot, no humming at all.
Anyways the problem is not the qudelix , but proper grounding of your wall sockets. A friend of mine had that problem, he went to the basement and put a long metal stick from the main power line of the house into the ground...since then every socket sounds audible better, I'm otherwisebreally bad in noticing small improvements, but THAT one was a large improvement ! Much much cleaner
