Valab DAC Question

Yes - that is the case on my and probably all Macs.

When you select the USB driver in the Audio MIDI Setup tool, you turn off the native "Built-In Audio" output which is what feeds the optical output.

FWIW I believe that the Valab prioritizes the USB input when it is live. The switch selects between optical and coax when there is no USB input. I say this because many DACs are set up this way.

To prove it would require a second source to test.

It makes it hard to A/B on the fly, but other then that it doesn't represent a problem for me.

I wanted to use the Valab as a source selector and was disapointed when I started to see limitations, but this is a huge disapointment if usb prohibits switching.

Sorry - I don't think that there is a way around it - I was hoping to A/B two different USB DACs - that's when I figured it out

Every multi-input DAC I have ever had gives preference to one input - in some cases you need to throw a switch, in other cases you literally need to turn off the source.

It seems that what you are describing is a pre-amp and a DAC integrated into a single case - which is a great idea

Perhaps someone else knows of such a unit

But don't give up on the Valab it's a terrific unit

Just posted in another thread regarding Kevin's (Valab) high current power cord. It is not safe as the ends spin while the jacket stays in place. At least it does not seem safe to me. He knows this but is still selling them this way.