How to use outboard gear.

I feel very stupid asking this question. I have an outboard preamp with eq. I also have an outboard compressor. I am recording my own vocals and am curious if there is a way to record a vocal track “without any outboard gear” then take the recorded vocal and send to the outboard gear so I can listen and make changes to the outboard gear to suit my voice? Once I am done I will then have my settings for when I record.

I did try and finally got a signal to the outboard gear BUT when I try and monitor the return signal I get horrible feedback so I am assuming I am doing something stupid with the routing. I have stereo “output 1 & 2” going to monitors/headphones. Going out a separate bus mono output “3” to the gear then coming back into mono “1” input". Again, it might not be possible to do this since I am hearing what I originally recorded but just curious. Not sure if there is a way to hear just the input signal so I can mess with the settings without hearing the original track.

The reason I am wanting to do this is I will then have the ability to adjust and listen since I am trying to do this myself without having someone to help with settings

You should be able to to route a channel to a different output and therefore not go to the stereo out. This should work but sounds like you are creating a loop somewhere. Do you gave direct monitoring enabled on your audio interface?

All you have to do is read the manual of your not mentioned hard- and software, or wait until someone with his crystal ball can see your setup…