Q: Can't find a parasitic drain?

Yes, your amp could be staying on. Feel it and see if it’s warm. Disconnect it to confirm. Using a low amp probe (amp clamp) around the battery cable is the easiest, most repeatable method to measure battery drain. Measure the B+ wire at the alternator as well. Feel relays for warmth and key out of the ignition while doing this. Remember it can take 10-30 minutes after running for all modules to go to sleep. If you pull a fuse then put it back it can wake up a control module. You have to leave it out and move on with testing. Instrument cluster and rear wiper motors are a possibility, too. There is a lot of electrical content in your car, so you may want to double check the fuses. You’ll also want to verify whether the battery really is good! If you are still having trouble, you can always get a certified technician from YourMechanic to come to your car’s location to diagnose your battery and let you know what needs to be fixed.