Do chargebacks usually get resolved in the buyers favor?

We are building a house and my husband bought all of the built-in speakers from a seller on Ebay. He had 1300+ feedback, 99% positive, seemed like a safe transaction. Turns out that although he was an authorized reseller of Polk (the speaker co), he was not supposed to be selling things on Ebay and Polk cracked down on him and I'm not sure if they took away his ability to sell all together or won't let him get items unless he can prove they're for a local install or what happened. He kept assuring us that it would be fine and he would get us the rest of the speakers (he already sent us 2, about $1K worth, we purchased $8K worth total) ASAP. Several weeks worth of excuses went by and now he's completely stopped answering phone calls, emails, etc. I checked his feedback page and the negatives have started flooding in from other people, obviously we will not be getting the rest of our speakers.

The 45 days to file a dispute in Paypal is long up, the original purchase was made Jan 27th, so I filed a chargeback with American Express.

I am absolutely sick over this. I keep hoping this is a cut and dried case of item not recieved, we have all of the emails back and forth with the seller and tracking on the original shipment that shows it was only about 20 pounds, which is obviously not the entire order because the order was for 23 speakers total which obviously would weigh quite a bit more than 20 pounds. I just have heard so many horror stories about Paypal and don't know how much power they have in a case like this to possibly not allow the chargeback. I've heard great thing about American Express and them getting things resolved for buyers but am freaking out that it's such a large amount of money they may not be able to. What a nightmare.
 
american express is really good about it! they get you your money first then investigate. but i think its really good that you kept the original emails and stuff. i think you should be ok

i did a charge back on a fake purse and they got it to me the same week. but i had to provide all correspondence between me and the seller. but i got my $ back