DAC connection to computer

USB is flawed. Why would you go from fiber to usb? You’re going backwards.

All dacs in preamps/integrateds are compromised compared to quality standalone dacs. 
It’s funny when people say don’t hook up a computer directly to your dac but every streamer is a computer.

There is only 1 streamer that has a galvanized input/output, and I use it with i2s into my dac.

@rbstehno stand alone DAC is my preference also since it isolates the conversion from both the computer's and the amp's electronics but OP is asking specifically about connecting his PC to the DAC in his integrated amp.

Ah.

"A streamer is a computer."

A single use box is totally different than a general use PC.

Galvanized, fiber optics, sales gimmicks.

+1 @travelinjack 

In addition to Foobar, you have the JRiver Mediacenter as another option for locally stored music. Connection from your computer to the Mac 7900 via USB A/B.

Using (for example) Quobuz as the source of music (PC app available), you can send the stream via USB to your DAC as well.

Give it a try. If you are satisfied with the soundquality, you will not need any additional hardware. If not, you may want to go with a dedicated streamer.

I am using an Android platform including USB Audio Player Pro going directly into the integrated amp via USB A/B (and as well via separate DAC to the amp).

It is all about personal preference.

Others have said it, but it is probably useful to summarize:

1) PCs are acceptable sources. Sonically the biggest issue with them is that they are not optimized for audio play back. They have inadequate DAC chips, they are prone to digital timing errors, capacitors are low grade, are prone to noise interference from the other functions of the computer, and other issues.
2) You need some sort of software program to manage music. Paid streaming services such as Tidal provide this. If you have music stored on a hard drive that you wish to play you need a program for that. Room is one service that helps you manage both in one space.

3) The OP has a DAC in his integrated amp and it surely will best the one in his computer. He therefore just needs to send the digital stream of the PC to the amp. The most common way to this is usb. Presumably the DAC in the amp offers other digital inputs but most computers tend to offer just usb as a digital output so his computer will probably be the limiting factor.

4) What is a streamer and should the OP buy one? Streamers are basically networking computers that have been optimized for sound. Some contain DACs. They also look like audio components.

The OP is obviously new to streaming. I am not familiar with his amp. McIntosh is a storied company. I can’t imagine that it would sound bad. Start there and stream from your computer. You may be so happy that you never feel the need to move on.

I used a computer into a DAC for several years before buying my first dedicated streamer. You can always upgrade later but since the OP already owns the amp and a computer it would be logical to start there