I did the same exact thing and purchased 2, one from apos and the other from shenzen. I'm pretty sure you've figured by now but they're essentially the same considering their shipping packaging are identical and it's likely Shenzen Audio is just the front they use for Amazon.
That being said I DO NOT recommend buying from Apos if you can help it. If you read their fine print on returns it's severely detrimental compared to if you went through Amazon:
- Orders that were price-matched against a final sale promotion are not eligible for return.
- Return requests made between 8 and 45 days after the order is marked as delivered will be subject to a 20% Processing Fee*.
I'm not sure if some of it is just a bad wording but from what I inferred if you price match an order you forfeit returning the item. I'm not too clear on what "final sale promotion" refers to though. This is especially bad considering they've
raised prices for 2021 roughly ~10% on most items in their store. The 20% processing fee on top of return shipping(to their Oakland HQ hopefully) is quite absurd as well considering you're given only a week after delivery to decide if it's for you. Personally 20% is the highest fee I've seen for returning something within a normal 30 day window assuming you return everything properly. There are more restrictions to returns but I only picked out the ones that stood out to me as out of the ordinary.
Unless you're adamant on not giving Bezos your money, I wouldn't consider Apos Audio my place to purchase audio gear under most circumstances.