It doesn't matter if you use optical out (the device in Windows is usually labeled something like "digital out") or USB. Either way, you need to connect the cable to your DAC. Some amps have a DAC integrated.
The DAC will receive the digital signal and convert it into an analogue signal. This signal is usually weak and cannot be used to drive headphones directly. Therefore you connect the DAC to an amp, which will apply voltage gain (=> higher volume) and current gain. Again, your device might have both a DAC and amp in it. In the case of a sound card the transfer of digital data takes place inside the PC over PCI (Express).
To output to this DAC or sound card you need to set the proper output device in foobar2000. There are several different choices for audio APIs (in simple terms a software interface to communicate with the audio device):
- ASIO: was developed for recording, low latency (which is not a requirement for music playback), provides exclusive access to the sound devices (no mixing with system sounds or other applications)
- WASAPI: new interface by Microsoft, can provide exclusive and shared access (the fb2k plugin provides exclusive access only) to the sound device
With these two you can only set the bit depth (16, 24 or 32 bits, use the highest supported bit depth for your device). The sample rate (for example 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz ..) will be set to the sample rate of the track you are playing. If your DAC doesn't support this sample rate you'll get an error message and playback will fail.
- DirectSound (short DS): legacy interface by Microsoft, still works perfectly fine though, on Vista/7 it is implemented on top of WASAPI shared mode (mixing with system sounds etc.)
With DirectSound you have to set both bit depth and a common sample rate in the control panel. This common format is used for all sounds from all applications which will be mixed together and sent to the DAC. But DirectSound can also be bit-perfect if you set the common format to the same format of the track you are playing. Otherwise, there will be resampling (sample rate conversion).
Originally Posted by Mshenay
I have a TosLink Optical Spdif out, once I buy the cord do I just run it into my DAC? Or into the an Amp...
In addition I'm looking at using a O2 DAC, do I choose the Null Out option In FooBar then hook up the USB to the O2? and ofc from there I'd run it to my Amp
O2 DAC is USB only, no optical input. The null output is a special device that does nothing. It's used for development.
Edited by xnor - 11/19/12 at 9:23am