Guitar to PC Interface using Guitar Rig 6

Software like Guitar Rig 6 is usually used to digitally emulate an amp using an audio interface and a computer. This is usually used in conjunction with a DAW (digital audio work station) or a stand-alone version of the emulation software. A popular choice for audio interfaces would be the Scarlett 2i2. This would be used if you wanted to jam or record on your PC. Software like GR6 isn’t typically used to play through an external amp but I’m sure there are some tutorials out there to help you out. You would have to turn off any cab emulation (impulse response) and route your signal back out through an interface or re-amp box then into the FX receive jack of your amp. Not sure I fully understand your specific needs but I hope this helps.

Yes it should have a headphone out and two balanced outs but the latter would be for studio monitors. You can use a 1/4 inch adapter to convert the headphone jack to RCA or whatever you need if you are using computer speakers. The Scarlett 2i2 is just one example of a solid interface and there may be cheaper ones out there such as the Scarlett solo or the motu or maybe something from audient depending on your needs.