Hi. I've posted something similar earlier but didn't really get to solve the problem then so I'll try again.
I use a Kemper profiler to record guitar. When I play the kemper trough the interface and studio monitors it's sounds juicy and big, with a nice balanced equipment. However, if I record the same sound, the playback looses low frequency and seems very harsh and high in the mid frequencies, more a cardboard feel. I've tried recording at 24bit and all the way up to 192KHZ but there's no change in the playback sound. I'm going directly from the kemper to the motu 896 interface with xlr, no spdif just analog between kemper and the motu.
I'm beginning to think that's it is the motu interface, but still I get very good sound when recording mics and synths.
Any sharp heads out there that can guide me?

first thing to check would be how does it sound when monitoring through the MOTU (as this includes the AD-DA from the MOTU), next would be to check if there any DSP options (e.g. EQ, compression) activated on the MOTU which add to the signal before it hits your HD (don't know what the 896 provides, but many interface have these options these days) ... others may have more ideas ...

I have an 896mk3 Hybrid.
There are options for recording in the Cuemix FX.  EQ, compression, etc.  Make sure the channel you are using does not have any of these options set.  Also, try a different channel.  On my 896mk3 Hybrid, if I use a 1/4" TRS connection instead of the XLR, I bypass the 896's preamp, try that too.
 
 

This is from your other thread,, you where using a Line 6 and had the same issue... 
 
"Follow up. I did the test and did find my problem. I had the Input Gain of the track at a non zero value. The Input Gain control is bypassed during record/monitoring but (of course) not in playback.
 
As the official signal flow chart clearly shows, it is a feature not a bug but something critical to pay attention if you use amp simulation with effects sensible to input volume (like compressors): 
 
Thanks to all for your answers."
 
 
You said your issue was solved. So not sure what could be different. 
You solution is odd. Sonars level controls do not make any difference to what is recorded. 
The signal goes from your A/D- directly to your hard drive as data. Sonar is only monitoring this signal to show you it's working. 
If input echo is "ON" then it would make a difference to what your hearing. 
There's no point in monitoring with input echo unless your using Sonars effect on the track and wish to hear them in realtime. There's a danger of also hearing latency unless your system is capable, which your should be at lower buffer settings. 
But I think you should try using direct monitoring and see if that is the problem. After all your using outboard effects on your guitar so there's no need to use input echo. 
It might be ( like your other thread) you have not figured out how to set your interfaces GUI mixer like Fireberd has advised. 

Hello, this isn't me but I will share try this solution :)