Sound Problems

First, the Kemper headphone amp is going to sound different than the Interface's headphone amp because they are different. If you have a Mix Knob on the Interface to monitor the original input from the Kemper then turning that knob from "input" to "playback or mix" will change the sound to the "processed D/A conversion" tone of the Interface which sounds different. Turning that mix knob to "input" should sound the same as the Kemper Headphone output because it bypasses the Interface.

The Kemper Headphone output is taken from the Kemper Main Outputs and are the same signal.

I had a quick look at the manual for you interface. It looks like the Mic/Line inputs are auto switching. If you use an XLR cable you will engage the Mic Preamp. If you use a TRS cable you will bupass the mic preamp. For connecting the Kemper you should bypass the mic preamp. Therefore, you need to use a simple instrument cable for an unbalanced signal or an XLR to TRS cable for a balanced signal.

Quote from Wheresthedug

I had a quick look at the manual for you interface. It looks like the Mic/Line inputs are auto switching. If you use an XLR cable you will engage the Mic Preamp. If you use a TRS cable you will bupass the mic preamp. For connecting the Kemper you should bypass the mic preamp. Therefore, you need to use a simple instrument cable for an unbalanced signal or an XLR to TRS cable for a balanced signal.

... all of the above, plus you should check the "Space" settings. By default it's active on the headphones output (to give you a touch more room feel) but NOT on the Line Outs on the back of the Profiler.

Quote: “I have a problem with the Kemper, it sounds radically different if I plug the headphones directly into the Kemper than if I connect them to the audio interface, it sounds much worse on the interface. “

It appears your problem is the difference you hear on your headphones switching between the Kemper and the interface.

Knowing nothing regarding your interface I checked its specification. Its headphone output is designed with a low/medium impedance of 60 Ohms.

Checking the specification of the headphone output of the Kemper its designed to operate headphones from 32 Ohms to 600 Ohms. Higher quality, superior in every respect.

Most studio headphones are rated at 250 Ohms for safety reasons to protect your ears, but the Kemper will basically operate any headphone you choose to use up to the very high-end audiophile equipment.

As a general rule of thumb, you can divide headphone impedance into several broad categories. If you read through the included link and scroll down to watch the video, it will illuminate your comprehension of the issues.

Impedance Guide | beyerdynamic

It may be that a set of headphones closer in impedance to your interface will deliver a better sound than you are currently experiencing. Whether it is desirable to keep changing headphones is another matter.

Quite regardless, the superiority of the Kemper’s professional design will always mean it will sound far better than your recording interface, unless you upgrade from a prosumer interface to professional level equipment.

The good news is I don’t believe anything is wrong, it’s probably just that one piece of equipment is vastly superior to the other. They are designed and manufactured for entirely different price points so this shouldn’t come as a great surprise.

If your headphones are high impedance and your interface is designed to drive far lower impedance equipment your interface maybe struggling to drive them properly; whereas your Kemper with its wide-ranging compatibility can make everything sound great, this to my mind may explain the difference you are experiencing.

Why not simply use the equipment you have for now, and let your ears and brain have time to learn to adjust to the differences, as perhaps you can adapt yourself to what you are experiencing.

With respect, ultimately, you will need to pay close attention to the specification of future equipment purchases and ensure there is qualitative matching consistency throughout your signal chain.

Its only as good as the weakest link. Perhaps you can eventually save towards a more professionally specified interface?

In the meantime enjoy the great sound of your find Kemper equipment!

I agree that switching to TRS cables should do it.

Check your output settings on the different outputs.

BTW: what do you mean with "infinitely higher"??? Higher in volume, EQ High or what?

I'm wondering if you are being confused over amp-in-the-room sound compared to the mic'd cab sound outputting from the interface. These two do sound different. Just about all users output to Studio Monitors from their interface because they give a flatter (or non-colored) sound to be able to mix the guitar tone properly to bass, drums, etc. I'm being basic in my explanation and there is a lot more too it than that. The purpose of an interface is "to record". If you never intend to record then a Kemper Kabinet is all you need to get a real amp sound.