oh...
thanks for info...
confused
here is what i read from acer site
Information about S/PDIF interface
What is S/PDIF and how can I use it?
Sony/Philips Digital Interconnect Format (S/PDIF) is a connection for digital audio, that allows a high quality transmission to a receiver or amplifier. It can be used for both compressed and uncompressed audio formats and allows multi-channel digital audio, such as Dolby DTS. It is available on selected notebooks and desktops.
SOLUTION
The completely digital S/PDIF connection can be used to connect the computer to a receiver or amplifier with digital inputs. For multi-channel audio, it requires support, for example Dolby Digital Live or DTS Connect. If such support is not available it will transmit stereo audio instead.
For S/PDIF connections, two different types of connectors exist:
Electrical RCA coaxial. This looks the same as most connectors used between audio components and uses an orange colour. This type of connector is not widely used on computers.
Optical fibre, called TOSLINK. This type of connector is fairly common on computers. It is typically available as a so-called mini-TOSLINK connector, which is the same size as a 3.5mm mini-jack, as used for headphones.
It is not possible to convert the optical TOSLINK signal to an electrical signal without the use of additional hardware.
In case your system is equipped with S/PDIF, the headphone connector serves a double role: as a normal headphone for electrical 3.5mm mini-jack, and as a optical mini-TOSLINK connection. In some cases, you may need to manually configure digital audio output to enable the optical S/PDIF signal. Use the following instructions, depending on your operating system, to manually enable S/PDIF signal:
Windows XP
Click Start, next Control Panel, and then select Sounds, Speech, and Audio Devices.
From the options available, click Adjust the system volume.
In the Sounds and Audio Devices Properties dialogue box, select the Volume tab, and click the Advanced button in the Device volume area.
In the Volume Control window, click Advanced. If the Advanced button does not appear, from the Options menu, click Advanced Controls.
In the Advanced Controls for Volume Control dialogue box, select the Enable SP-DIF, SP-DIF or Digital Speaker check box.
Windows Vista and Windows 7
Click Start, next Control Panel, and then select the Hardware and Sound category.
Under Sound, click Manage audio devices. In the window that opens, a number of devices may be listed under Playback.
Among the listed devices, select the device described with Digital Audio, and click Set Default. A green tick mark should show that this device is now the selected output device. Click OK to confirm and close the window.
MORE INFORMATION
In case your system is equipped with a HDMI connector, it is recommended to use HDMI instead.
