Cats can get the mites which cause sarcoptic mange and notoedric mange. These are diagnosed with a skin scraping. Ear mites are a different species, and normally live in the ear canal. However, occasionally ear mites do spread to the skin around the ears.
It's possible one of these mites is ocurring with your cat. If he is very itchy, I would be more suspicious of mites. If he's not itchy, I still think chin acne is likely. The acne sometimes presents as a sore, like your boy has.
As a precaution against mites, apply a dose of Revolution to the back of his neck. This is a safe and effective treatment against ear mites and fleas. It's available from your vet or online. If he has a mange mite, he will need veterinary treatment.
Regarding his ears- cats with ear mites typically are itchy, and have a dark discharge like coffee grounds. Your vet can diagnose this by using the otiscope, or looking at a sample of the exudate under the microscope. Itchy ear can also mean simply a waxy buildup, or a yeast infection.
To sum up, to diagnose the mites for certain, bring him to your vet for an examination +/- skin scraping. If he's itchy, treating him with Revolution is fine to try first. I would also do the cleaning routine with the Pyoben shampoo in any case.
I will be here through the day if you have further questions. I appreciate your patience with the process.