My setup is the CA azur 640c v1 using the AQ king cobra rca running from the CA into the Creek 21se headphone amp and then using the the Sennheiser HD 650 with Cardas cable as my speakers.My question is what's wrong with the built in DAC?I've been wondering around the internet and people are paying good money for a seperate DAC to by- pass the CA azur 640c's DAC.If anyone out there who is using a seperate DAC can you tell me what's wrong with the DAC I'm using.Does a seperate DAC sound better? Or are seperate DAC's now becoming obsolete?Also understand that I'm quite impressed with the set up I just descibed.Thanks