The biggest flaw is the female voice screaming with the hilarious pronunciation of either connect-aid or disconnect-aid. You definitely know when you're connected but it is best to do so without your IEMs inserted in your ears. The c-pin is exactly what I wanted for the KZ Sonata to go portable as they kept falling out of the TRN set. The pro model probably offers additional audio codecs but I find the AZ09 sounds great and is capable of pushing the volume higher than I listen at. Overall, I'm very satisfied.
