Mac Pro - went quiet today

Mac Pro running Mountain Lion. Audio working just fine this morning, didn't change or touch anything, and this afternoon it's quiet as a mouse. No sounds at all. Have restarted, have checked all connections, have checked output in system "sounds" preferences.... bupkis. No sound.

Any clues?? The ever-helpful Apple user forum has been utterly silent on my question posted there. Surely I'm not the only one this has ever happened to? All of my Google searches come up with fixes for Macbook Pro's not desktop Mac Pros.

Tks!

B

Since the audio chipset is integrated to the logic board in your Mac Pro, suggest running the Apple Hardware Test to see if picks something up about the audio not working. AHT LINK

Several issues:

1. When I restart I can hear the startup chime on the internal speaker (this has always been *barely* audible on this machine, but it's there). That tells me that the problem doesn't reside on my mother board. HOWEVER, if I play something in iTunes at full volume, regardless of whether my sound control panel is set to "Internal Speakers" or "Line Out", I can't hear anything at all. This perplexes me.

2. I only have one disk that came with the machine (I believe that's the only disk I got with it). It's labeled "Mac OS X Install DVD". It is a bootable disk, but holding down the "D" or the "C" keys when starting up from it only gets me to the install menu, and there's nothing about Hardware Test in the "Disk Utilities" menu it contains.

3. If I remove the OS X DVD and try starting up while holding down the "D" key, absolutely nothing happens except a normal startup.

Ideas??

Tks

B

You should have received two disks with the machine if it came preinstalled with Tiger, Leopard, or Snow Leopard. Did you buy the machine new or used? And which version of OS X are you running?

If I ever did have two disks, I don't any longer. I've moved house three times since I bought the Mac Pro, and if the disk isn't in the same place as the other one, then it's long gone.

So, I still have a silent Mac Pro, no 2nd install disk, and no way to fix it.

Anybody have any other ideas? I've Googled and I can't seem to find a source for the disk. I'm stuck..

Tks

B

No the AHT was the go.

Done an SMC reset?