Newbie Question on Selecting USB Output

My main system is non-computer based, but I'm thinking of connecting a relatively inexpensive USB-DAC and comparable speakers to an office computer. My question is, does merely connecting the USB-DAC to the USB output jack on the computer cause the computer generated signal to go to the USB port or do I have to change computer settings to bypass the computer's sound card? And if I have to change a setting, does it involve merely clicking on a different choice or will I have to install something?

I'm using a Dell PC running Windows 7.

Thanks for any help you can provide.
Yes, you need to select the USB-DAC as your output. The PC will recognize the device but will not choose it automatically. Undoubtedly, there will be instructions included with the DAC.
I'm running 7 on several pc's. When I hook up a DAC, the PC recognizes it automatically. My main pc will even disable the 1/8" speaker jack when I plug in a DAC. I guess it depends on your soundcard?
You have to tell the PC to use USB for audio out, but its very simple.

You may have to install drivers, but it depends on the DAC. Some you do, some you don't.
Thanks to all for your answers.

I can connect the DAC and see what happens, but I will be prepared to select the USB port. Also, I definitely will ask the seller of a DAC if a driver has to be installed.

I have hardly any experience setting up computers, but I'm assuming that if a driver is required, it will be specific to the particular DAC unit and be included with it, and not be some sort of generic driver for DACs in general that I buy separately. Is that correct?
Why not just have a look at the manufacturers web site and see. If you do need a driver, they probably have the newest version for download.
Here is what I do and it works flawlessly for me.
1. Go to the DAC manufacturer's website, download the current driver for your DAC and install it.
2. Connect the DAC to the USB port and reboot the computer.
3. Click START> CONTROL PANEL> SOUND. Your DAC should be listed in the dialog box that appears. It may be listed as both "Speakers" and Pass-Through" device. If so, click the speaker option for your DAC and click the SET AS DEFAULT button just beneath the list.
4. Next, click the PROPERTIES button. A dialog box with three tabs at the top will appear. Click the LEVELS tab and adjust the level to 100%, then click the ADVANCED tab and select the proper setting for your DAC from the drop down list you see there. Click the TEST button to verify that your settings work. Make sure both the boxes in the EXCLUSIVE MODE section are checked and click apply.
That's it! You should now be able to open your media player software and listen via your USB DAC.
One final note. If you don't have any other sound devices connected through the computer's sound card, I would disable it in the computer's DEVICE MANAGER, as you no longer need the sound card.
Good luck.