VST - input monitoring

is there a way to make it so input monitoring on a track will ONLY play the sound coming from the VST program, and not monitor the clean signal?

 
That is exactly how input monitoring with FX plug-ins in the track FX bin should work by default - as Inserts. If there's any clean signal coming through, it's due to a mix control in the VST being set  less than 100% wet (usually desirable, but maybe that's not what you want...?).  Setting the VST's mix control to 100% wet will give you only the sound of the effect... unless you also have direct monitoring enabled on your interface; if you don't hear any signal until the Input Monitor is enabled, that's not the problem.
 
If the effect is on a bus, and you're using a send to that bus, you would need to set the Send to Pre-fader, and mute the track to have the FX's mix control be in charge. So if you want a 100% wet effect, put it in the FX bin.
 
 

Sorry for the slow response. Thread dropped off the front page before I saw your reply.
 
I think the confusion might be in the way Guitar Rig works; it's a little different from most plugs. You might want to check out the PDF manual.
 
First off, there is a Matched Cabinet component in many presets with a Dry/Wet control. That's not the one you want.
 
There is a button labled PRST in the GR toolbar that opens a Preset Volume module.  You then have to expand that module with the + button to see the Dry Volume, Mix and Wet Volume controls. You can reduce or eliminate the dry component either by moving the Mix control toward Wet, or by lowering the volume of the Dry signal.
 
Note that if you turn off all the components in the rack, that bypasses everything so you hear dry signal on the Wet side of the Mix.
 
Regardless of how you have GR set up, however, what you hear on playback should sound essentially the same as what you hear while recording. Unless maybe there's some mild feedback while recording that isn't there on playback because you've disabled input monitoring...?
EDIT: On second thought, any feedback would get recorded, so that's not it. All I can suggest is to start with some really simple rack in GR and do some experimentation.