So what I'm trying to do is record dry guitar tracks into Reaper, and use an amp for live/no latency monitoring while I track. Very similar to what this guy is doing in this video:
Im running my guitar into a Presonus Studio 192 mobile interface. I have the main outputs going to my monitors, and output 3 going into a small amp. My goal is to have output 3 be a dry signal of just the guitar.
Currently Reaper is playing all of the tracks through the main outs just fine, but it is also playing all of the tracks through the third output as well.
This is happening even though I only have "main output left" and "main output right" selected for outputs, and regardless of the audio system + drivers that I select.
I have "Studio 192 Asio" selected for a driver, which creates a button that reads "Asio Configuration", but clicking the button doesn't seem to open anything.
I have also tried changing the device settings in Studio One, but clicking on the "device settings" button doesn't seem to do anything. I also tried to change settings in Presonus Universal Control, but didn't have any luck.
What am I doing wrong?
In Reaper, you can use the routing matrix (ALT+R) to configure all your I/O. Maker sure your master track is only going to output 1/2 (stereo). Find your guitar track on the left side of the matrix and click on the grid that it shares w/ output 3 to send it to your amp. If you can't see output 3, then go to Audio -> Device and maker sure you have (at least) up to output 3 selected as the last output. I don't use this setup, but I'm just going off of what I know from using Reaper myself. Hope this helps!

Edit: Just thought of something: Reaper is probably calling your main outputs 1 and 2, which would mean that output 3 on your interface would actually be output 5 in Reaper.
Last edited by BlackFalcon17 at Aug 30, 2016,
In this case you need a DI:

In this case preamp is your interface.

Any other way will most likely bring unneeded complexity and latency.

You can get a cheap passive DI like a Whirlwind or something a bit more fancy like Radial.