Add me to the people whose AP80 broke soon after received and who will never buy a Hidizs product again.
Bought it direct from Hidizs for an excellent price ($112.50).
After a lot of messages from me at various places Hidizs did respond.
Basically the same experience most people have had: after making me provide some receipts, they made me try reflashing the firmware and resetting the settings to the defaults, then advised me I would need to ship it to China for them to check out, but I would have to pay shipping and taxes.
The cheapest shipping price I could find was $35.
Like almost everybody else, decided against shipping it back.
On Amazon, one reviewer did ship his to China, and reports:
"First unit stopped functioning after a month. It took me three months to get Hidiz to respond and after paying shipping ($25) to china another two weeks to get a replacement. The replacement lasted a week. I will never buy another item from this company. Not recommended!"
When mine stopped working:
I was in the middle of listening to Reference Recordings Saint Saens Organ Symphony 4th movement, when the great sound suddenly turned terrible.
Volume was halved and sound quality much worse.
Tried playing some pop music and lead vocals were distant echos, like left and right were combined and center audio information cancelled out.
Also no more radio reception.
My theory is the jack's ground connection went bad.
No stress was being put on the jack when things went bad: it was just laying flat on the bed next to me, running off the battery, no charger attached.
Its held together by glue, not screws; I saw the FCC images earlier in this thread, its very involved, so I won't be trying to fix the jack.
Just recycling/trashing everything they sent me.
Fool me once, shame on them.