Assistance with Input Volume

At home, I am using a PreSonus Audiobox USB audio interface. If I plug my guitar directly into the interface and turn the gain know on the interface for that channel all the way down, in many cases, it still clips in Reaper. I don't have active pickups in my guitar, and of course, turning down the volume knob on the guitar, it effects tone, depending on what the desired effect is... That said, what more can I do if the input at lowest gain on the interface is still too high?

Not familiar with Audiobox, but I find the following quote from the user's manual to be suspicious: "Power User Tip Active instruments are those that have an internal preamp or a line-level output. Active instruments should be plugged into a line input rather than into an instrument input. Plugging a line-level source into the instrument inputs on the front of the AudioBox USB not only risks damage to these inputs but also results in a very loud and often distorted audio signal." Do you have active pickups on your guitar, by any chance?

The audio interface only has two inputs, and they double as xlr or 1/4" jacks. The guitar has passive pickups

Turn DOWN your guitar volume on your guitar. It's completely safe and will not damage your tone in any significant way. Or, if you have some money that you desperately need to get rid of, get a passive DI-box of some kind, it does NOT have to be expensive to do it's job perfectly fine. You should be able to get a decent one for around 10$.

I know I can turn turn down the guitar volume, but that does affect tone. If you plug into a real amount, turn on some crunch or distortion, then roll back the volume on the guitar, it will most definitely change the tone. However, if I can keep the volume pot at full on but reduce after the fact, that may work.

Perhaps I have a bad unit then. I also have an Akai interface that doesn't have this problem. Honestly, it seems that turning the knob has zero affect. I'll call Presonus. May need an RMA

Sorry correction 9 o'clock. I was looking at the wrong channel

Taking just a cursory look at the PreSonus Audiobox USB audio interface it sounds like the unit may have a problem considering you have a passive pickup guitar etc. I take it you are using channel two on the unit for instrument. Might pay to drop PreSonus a line? Grinder Footsteps to the Sun

Get yourself a cheap used line 6 pocket pod, and record the output signal of that. This unit will not only supply effects, but will also act as an impedance changer / preamp.

First, turning down the volume knob on a guitar with passive pickups can/does affect the sound due to impedance and loading. This mostly a loss if treble. Doing this will also affect the gain/tone of the amp sim, but this can easily be corrected with a gain trim plugin before the amp sim, or by adjusting the input gain on the amp. Secondly, if your levels are too hot with the gain at minimum on your interface, engage the pad. If your interface does not have a signal pad, use a DI that does. This is a common issue with low end interfaces, I have the same problem with my focusrite 2i2 and use a DI.