[bleee]

Why is it that if you use the optical out port, you can still adjust the volume in iTunes? I figured that optical out is just a plain line out but digital and that it was up to the receiver to control the volume? Yet in iTunes even with my logitech 5500 using optical out cable iTunes still allows me to adjust the volume?

[analogika]

You need to distinguish between the master out (which is what is controlled by the volume keys on the keyboard, or the menubar volume item), and the individual levels for each application.

Every application that outputs sound - DVD player, iTunes, VLC, every single Finder preview, QuickTime, and the System beep - has a separate volume setting RELATIVE TO the maximum system volume. Structurally, it's akin to having separate faders on a mixer for every source, with a master fader for overall volume.

[bleee]

But the thing is in iTunes when you change the source to an airport express the volume control in iTunes is locked at max now does that mean its outputting at the highest volume or acting like a line out? I would prefer if there was a way for my mac pro to act as like a digital line out and I control the volume from my receiver.

[analogika]

If you change iTunes' output (not the source) to an airport express, then you're not sending it to the computer's audio output, are you?

Also, the iTunes volume is only locked to the max when you send it to an Airport Express IF volume control is expressly disabled in the iTunes preferences.

[bleee]

does this mean there's not way to get os x to just output a straight optical line out signal with no volume boost?

[Gossamer]

Originally Posted by bleee 

does this mean there's not way to get os x to just output a straight optical line out signal with no volume boost?

There is no volume boost, only volume reduction. Putting iTunes' volume at 'max' sets it and the minimum line out volume. Anything lower than that makes it quieter. Whenever my computer's sound gets amped, it's at full volume from the computer.