Just got the Fiio DM13, but the audio sounds super muddy and bass is distorted when connected to home audio

Hello,

So I just got the Fiio DM13, and have it set to PRE OUT. I have it hooked up via 3.5mm to RCA to my Fosi Audio Box X2 preamp, and then that is being sent to some powered speakers. It sounds super muddy and the bass is distorted. However, when I hook up the RCA cables direct to my powered speakers, it sounds fine.

Does anyone know why this is happening with my preamp and how I can fix it? I tested my preamp with my record player and it sounds great, so that rules out a preamp issue. Thank you in advance for any help!