Transport/DAC upsample question

In a transport/DAC combo,which unit upsamples the signal?
For example,a PC (or any transport which doesn't support upsample) connected to DAC which supports 24/192khz upsample.Does upsample happen or not?Do you have to bring already upsampled signal to DAC?
Do transport and DAC always have to match with the same upsample characteristics to get the best results?
Maybe for some of you a-goners this is basics,but i'm really not certain about this.
Typically the DAC does the upsampling. This could be a standard upsampling frequency, say 24/96 or 24/192, or some DACs allow you to select the upsampling frequency

However, my North Star transport also upsamples. Using the XLR output I can set a switch to allow 24/96 upsampling. Using the I2S output I can set a switch to allow for 24/192 upsampling. If I do this, then in XLR mode I can upsample the 24/96 signal to 24/192 at the DAC (which also happens to be a North Star), or with the I2S mode the DAC just accepts the 24/192 signal and passes it through.
Hey BB,

The answer to your question might be somewhat manufacturer dependent but one thing is certain, the interface between the transport and DAC will determine what sample rate is being communicated. In the most likely situation, the transport will be connected to the DAC with a S/PDIF connection. This Sony/Phillips Digital Interface is defined as a 44KHz 16bit data interface. Even if you are using a balanced interconnect, the data interface is the same. Some manufacturers have proprietary interfaces that use a different data communications interface. These interfaces might support higher data rates and the transport could in this case do some up/over-sampling. In any case it is most likely that the up/over-sampling is done in the DAC.

The Theta Digital web site has a good article on up/over-sampling at:

Hope this helped,

BB, a "transport" only reads data contained on a disk. It doesn't sample (upward or downward). The D(igital) to A(udio) C(onverter) does that.
So, no problem. All you need is an output fm the transport (usually labeled "digital out" on cdp's). Cheers
As simple as it was for you,Greg,for me it was valuable.
Thank you for all your answers.For my office,I'm thinking about a PC based system connected thru USB,then converted to S/PDIF (with converter) and sent to DAC thru S/PDIF cable.I guess this means that both in USB and S/PDIF cable there will be 16/44.1 khz signal.DAC upsamples,converts and i can enjoy while working.
Audiobb - the USB converter can provide upsampled data at 24/96 to the DAC if the upsampling takes place on the computer, such as using SRC for PC's.
The system is done for now.I will upgrade on amps and ICs and digital cable.I use PC as a source and a non-upsampling DAC.Audio Note DAC 2.1 Signature.Works in 16 bit / 44.1 kHz.
Result is excellent.MUCH more than i imagined.It does have musicality,an analog-like quality.Rhytm is great,bass is very good.No high-frequency hiss (which we noticed during earlier testings).Which is very strange because i am using 10 metres of cheapest digital cable and 1.8m of normal USB cable.I can't wait to upgrade.
I also invited a friend of mine,the constuctor of tube-amps,who is for more than 10 years in tube gear.He was amazed,and also was i.I can't believe that PC can sound this good.