I'm a new owner of a used Concero HP. I use Audirvana+ on my iMac (OSX 10.9.5) and I have a question for similar users. Under the Mac's System Prefs/Sound/Output settings, do I choose Concero HP or leave it at Internal Speakers? I should point out that I have another DAC/amp attached to this Mac but it uses a different USB port from this. Thanks.