Changing USB input on DAC to Coax SPDIF?

I may not be totally following you but if what you are trying to do is to use the spdif (rca) input on the DAC vs the usb input have you looked into a usb to spdif converter? The usb cable from the computer goes into it and then a digital spdif cable goes from the converter to the DAC.

link below is just an example of a converter , there are a few other manufacturers

@musichead  - Are you talking about the USB input on a Rega Isis CD player? I have the Rega Saturn-R and I have connected my Raspberry Pi based Stream to the USB input on my Rega Saturn-R and it worked with no issues.

What is it that you want to connect to the Isis via USB?

The Isis is the same design as the Saturn R, the only digital input is USB. Does the Raspberry Pi require the Rega driver installed on it? I'm looking at simple streaming options like an Ifi Zen Stream vs a laptop. I want to stream from a hard drive with ripped CDs from a devise that is simple and avoids most of the computer noise issues. A computer requires a driver installed to work, will the Ifi work through the USB connection?

An Amanero board is the cheapest solution. In a case:. 

Tenealay. 

After that you need a DDC, $440 on up.

Windows PCs will often require a special USB driver to worth with asynchronous audio inputs on DACs. Most audio streamers and Mac computers will not require a driver.

Even though your DAC indicates that the USB input is designed to connect to a PC or laptop, I would expect that it will work with any streamer that features USB audio output. 

@jaytor The need for the USB driver on a laptop is the issue that confuses me. Doesn't the driver help the computer recognize and function with the DAC? But why does a streamer like say the Ifi Stream not require a driver to do the same thing? Is there a universal standard between audio devices that is missing on computers? Just trying to understand because my first idea was to replace the USB input with a COAX input.

@musichead  - No driver needed for the Raspberry Pi running Volumio. I found it to be very simple to build and set up. I think it sounds pretty darn good.

So, I actually have 2 Raspberry Pi based streamers. One is just the RP board in a case, with a cheap power adapter. The other has an I2S DAC Hat on top of the RP board, so it outputs analog. I have a higher-end power adapter from iFi for it.

Both sound great. If you only have a need for one streamer, build a Raspberry Pi streamer, with a quality DAC Hat on top and run Volumio. Then you would have both USB output, that you could send to your ISIS, and you would also have analog output that you could send to your pre-amp. Choose when one you like best.

Obviously, if you own an ISIS, the $100-200 expenditure is not going to hurt to much. It's kind of fun to build and set up and it is effective and sounds pretty darn good.

BTW, I usually control mine from my laptop because I'm often using my laptop as I listen to music. However, you can also control Volumio from your phone or a tablet. Works really well IMHO, especially since its free. However, if you want native support for Tidal or Qobuz streaming, you have to upgrade to the subscription. Not to worry. Both levels of paid service from Volumio are less than $100/year.

@musichead - For some reason, MSFT has chosen not to include this driver as a standard part of Windows. Not sure why. Most streamers are based on Linux and already include the required driver.

You can also run Logitech Media Server and picorePlayer on Raspberry Pi and get free Tidal and Qobuz streaming. Works easily with USB Dac connection or get a hat and use SPDIF.

The Tidal interface through LMS isn't as nice as regular app, but works.

By free, meant the picorePlayer and LMS app. Not Tidal or Qobuz? Just to be clear:-)