Sorry if I'm a little vague, as I don't know the correct terminology for some of this. I just recently started tinkering with this stuff.
Anyway, I've tried this with both my POD X3 Live and GSP1101 (Even though I have the modded firmware for the 1101 and can use IR cabs internally on the rack unit. It was just to test.) But I get the same results with both.
For me, the lack of IR cabs for the X3 leaves a lot to be desired. Especially after hearing what a difference they make with the 1101.
Since you can't use IR cabs internally with the X3 (to my knowledge), what I'm trying to do is use the X3 for the effects and use a cab simulator like keFIR to run the IR cabs in "real time" in either Reaper or Cubase. But every time I click the speaker icon to hear it "real time" in either program, I get this double-voiced sort of robotic sounding garbage that I can't get rid of.
I've seen this done where they have the X3's output running into the line-in on the computer's soundcard and they just mute the line-in in the soundcard's properties and everything works fine. But I'm trying to avoid the line-in on the soundcard and just use the USB output/input on the X3 like I have been. I tried muting it in the X3's properties, but it did nothing.
So, is this even possible? What do I have to do?
If I'm unclear or missing any info, just ask me and I'll try to straighten it out.
I used to do this with almost that set-up, although I did also have an external soundcard to use, which might be the key factor in not hearing the unprocessed signal whilst tracking.
What's your soundcard? If it's the one stuck on the motherboard, ignore it and use your Pod through USB. You'll almost certainly run into weird noise problems with live monitoring, otherwise. The price of this is you'll need to have your speakers/headphones plugged into the Pod to hear anything.
In Cubase, click Devices - Device Setup - VST Audio System and select Pod XT from the top-right dropdown list.
Plug your monitors/speakers in to your Pod, plug your guitar in and play to see if you have sound coming out. If you do, so far so good.
In Cubase, create a new track, load up KefIR as an insert and load an impulse into it. Then click the little speaker icon on that track to enable monitoring and play. You should now hear the track with the impulse applied.
Unfortunately, you'll probably be able to hear both the processed sound going through Cubase and the awful amp-without-a-cab sound coming through the Pod. I don't know how to mute that, as I always used my soundcard to control that. But, if you enable the device as your sound device in Windows, does the mixer or the Pod's control panel give you any options to control that?
Regardless, if you can't, the recording will still be perfectly fine. It just means you'll have to put up with that tone whilst tracking. Not ideal at all, but you can get stuff done, at least.