hi all - hopefully someone has the answer. i’ve searched the forum but did not find any answers. i’m trying to use my stereo headphones instead of my rockit monitors…when my kids are asleep late at night 
i have a dell 435 i7 tower running cubase 5 with a delta 1010 soundcard that has no headphone output. i would think that i would have to plug the headphones into the tower soundcard and change the driver in cubase? Anyone have any specific details i should look for. thanks in advance
Add a small 8 channel external mixer. This will not only help normalize your inputs and outputs, but should provide you with a proper headphone and monitor control. In addition, depending on the device, you may have built in effects (even if not using them in your final mixdown, they can be handy for direct monitoring) plus built-in HW EQing which might help reduce the plugin load on your CPU. There may also be diverse specialized in/outputs (e.g. dedicated CD, tape in/out etc.). The cost of such a device need not be excessive, check out Behringer, Mackie or Soundcraft among others, also ebay offerings.
If you’re really serious, think about replacing the soundcard with a new one which provides the ins and outs you need (including phones). Also invest in a pair of proper professional headphones as opposed to conventional stereo headphones which I presume you’re using now.
A headphone jack might not be on the sound card in the back of the tower but have you checked for a headphone jack on the front of the tower? Probably right near the front USB ports but maybe behind a cover of some kind. I would be very surprised if one was not there. Good luck. 
Regards. 
You didn’t read the OP very carefully did you?
I read it again and I’m not sure what I am missing/misunderstanding.
The op states that his/her computer sound card does not have a headphone output. As an alternative to what BriHar suggested I mentioned that there might be a headphone output jack on the front of the tower. If the OP is running CB through that sound card to monitors, and if there was a headphone output jack on the front of the tower (which a Dell 435 should have) it would be as easy as just plugging headphones in there which would (usually) disable the monitors. That’s a easy fix for listening to CB through headphones while kids are sleeping.
Of course the OP can purchase a PreSonus HP4 headphone amp like I have and run the monitors through that and have (4) headphone outputs but it sounded like he/she wanted to work with that sound card and BriHar already suggested purchasing an external mixer.
Regardless, I hope BriHar’s or my suggestion helps the OP.
Regards