shipped with some type of assurance that the ad is not a scam, that the amplifier is in full working condition and that it is not damaged either before or during shipment?
There is no such things as these guarantees you want.
Is this something that PayPal would handle?
Of course no, after Mr.Elon sells PP its user policy has become bulling.
every 6 months they send me an email threatening to cancel my profile and arrogantly ordering me to inform them of my documents and my monthly income.
Are they really able to discern a scam or protect for damage?
They are a Bank, they transfer money for you, you need a private eye.
If your equip arrive damaged or DOA, after two months PP custumer service solution will be return the equip to the seller at your own expense and PP will refund your money.
How do I avoid paying VAT for an item that leaves Europe and should not be charged?
You must ask the Tax Free option to the seller, maybe he can do it for you.
What is the best freight company to use?
This does not exist, in my experience all are expensive and dangerous.
Search Fedex Fail in YT.
