Volume buttons on iMac keyboard dont work when audio jack plugged in

Hi all
I recently bought an audio cable (Toslink to Mini Digital Optical SPDIF Audio Cable) to connect from my iMac to my surround sound system. The 3.5mm analog end of the cable goes in to the computer's audio out and the optical/digital end goes into the speaker port. The wire works fine but once i connect this "analog-to-digital" cable, the volume up and down buttons on keyboard dont work. Also the volume icon on the menubar on the top of the screen is shown disabled. Can anyone please suggest me some solution to this situation.

If you need to see what type of wire it is, you can check the wire here.
StarTech.com THINTOSMIN6 Toslink to Mini Digital Optical SPDIF Audio Cable, 6-Feet (Black): Amazon.ca: Electronics

Thanks in advance
Sazzad

Hi all
I recently bought an audio cable (Toslink to Mini Digital Optical SPDIF Audio Cable) to connect from my iMac to my surround sound system. The 3.5mm analog end of the cable goes in to the computer's audio out and the optical/digital end goes into the speaker port. The wire works fine but once i connect this "analog-to-digital" cable, the volume up and down buttons on keyboard dont work. Also the volume icon on the menubar on the top of the screen is shown disabled. Can anyone please suggest me some solution to this situation.

If you need to see what type of wire it is, you can check the wire here.
StarTech.com THINTOSMIN6 Toslink to Mini Digital Optical SPDIF Audio Cable, 6-Feet (Black): Amazon.ca: Electronics

Thanks in advance
Sazzad

I might be wrong .
But if I search for that cable on the internet it is standard optical cable .
So once use it from optical out to optical in
Controlling the volume happens on the analog side of the optical in

Thanks Dobby. Although i am not very clear on what you said. the cable is optical for sure. but the two ends are different. the audio out port (not optical port as imac does not have optical port) supports the standard 3.5 mm minijack. the jack at the other end is optical and also goes into an optical port. Its like a cable without having to use a converter between analog and digital ports. But i dont get how that disables my volume option in the computer. once i use the normar RCA cable, the volume option comes back again. Please let me know if i am missing something and is there any way to fix it up.

That's because the optical signal you're sending isn't modified by your Mac. It's a fixed, un-amplified digital stream. It's just data. It's down to the receiver to interpret, convert, amplify, output the signal.

@MSH

Please do not cross post or double post. Post your question once and to the same forum. Be patient and wait for an answer. Thanks.

MSH said:

the audio out port (not optical port as imac does not have optical port) supports the standard 3.5 mm minijack.

Click to expand...

Your iMac does have an optical port, your using it. The 3.5mm jack is both stereo analogue and digital optical. It auto switches depending on what you connect to it.

Optical cables can have two different connector types - a 3.5mm jack with a tiny hole in the tip for the optical connection and the small square jack with the two angled corners that you typically find on receivers/amps/cable boxes etc.

once i use the normar RCA cable, the volume option comes back again

Click to expand...

That's because the analogue out from this cable is analogue and pre-amplified by your Mac - hence you have control over the volume