Two hours is ample time ... ATH airport is just one big bulding int'l at one end, domestic at the other. The "Customs" thing is nothing ... it's a walk-through. What takes a bit of time is the passport clearance line, but that AA flight is the only one before 9:30, and it' will just take about 20 minutes... takes that long anyway for your luggage to reach the carousel. When you exit the luggage area, there is a sign "Customs: do you have anything to declare" and of course you dont... just walk thru. Then you hit the ATM machines for some Euros, and head over to the Aegean air check-in line. You just have to be in that line 1 hour (or 45 minutes) efore your scheduled depature. BTW, if you want a snack before your connection, get it before going thru the domestic security line ... there is not much in the domestic departure lounge.