Re: Changing the way the OS responds to a USB DAC
Re: Changing the way the OS responds to a USB DAC
- Subject: Re: Changing the way the OS responds to a USB DAC
- From: Brian Willoughby <email@hidden>
- Date: Fri, 02 Mar 2012 17:18:44 -0800
You are barking up the wrong tree. If you want the volume to be
"disabled" then you need to insure - as the user and operator - that
the volume is set to 0 dB.
CoreAudio treats each audio device according to the controls
advertised by that device. If a USB Audio device does not have
volume, then volume will not be enabled. It's not that the volume is
there and disabled, it's that there is no software-controlled volume
on that hardware. The reason that the optical digital outputs have
volume controls is because Apple's built-in driver provides a volume
control to CoreAudio. The reason that your Beresford and Fiio do not
have volume control is because of the USB Audio Descriptors. The USB
Audio Class Specification defines a standard way for each Device to
communicate its capabilities.
If you want to alter the hardware and software abilities of a
specific device that you are not manufacturing yourself, then you're
really asking for trouble. The CoreAudio mailing list and the USB
mailing list are Apple's avenues for supporting third party hardware
and software developers who are creating their own products. I get
the impression that you are a user who desires existing products to
behave differently than intended by their respective manufacturer, so
you're getting into the realm of hacking. I don't think that Apple
has a support line for hackers. :-)
You could file a suggestion with Apple that they add a feature to
their built-in optical digital audio output that would force the
volume to unity gain (0 dB). That would be compatible with a more
audiophile expectation, although it might be contrary to the general
expectations of a non-audiophile user. Apple is in control of
whether their built-in optical output presents a volume control, so
use the feature suggestion facilities to communicate your desire to
Apple.
Brian Willoughby
Sound Consulting
On Mar 2, 2012, at 13:14, SB Tech wrote:
I've received no responses to this. I'd appreciate being told
whether I'm barking up the wrong tree or people here just don't
know anything. If I haven't heard anything by Monday I'll remove
myself from the list.
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