What credit cards do you use?

A while back I was looking through the forums with someone mentioning that they just purchased some speakers new from the dealer. The cost was (for me, anyway) extraordinarily high, much more than I've spent in car purchases for my entire life. But then I started thinking, what kind of credit card did that person have to make that purchase? (Or was it a check, or cash?)

Do any of you use premium credit cards (AmEx Platinum, Chase Sapphire, etc) to get extended warranties, refunds if you don't like it, air miles, etc for audio purchases?

Michael