Recording guitar/bass through OP-1

Hi all, I’m new here so please forgive what may be a newb question.

I’m trying to run my bass (or guitar) through the line in on my OP-1. I’ve seen others do this and the tone of the instrument is great. However, when I play from my DI box (SansAmp Bass Driver) into my OP-1 the sound is low and the signal is distorted. I’ve tried adjusting input volume on the OP-1 using the sampler and, while it does affect volume, I can’t get a clean non-distorted signal.

Is there something I’m missing? Any ideas?

Thank you!