I'm using the CYNOVA USB-C to 3.5mm adapter to connect external wireless mics to the OSMO. The pre-amp quality is completly unusable. It's all mids with no lows and highs. Has any one else experienced this? I'm running the latest firmware. If I disconnect the wireles mic and record into my iPhone with the same set-up it sound flawless. Are there any audio EQ settings that I might have missed? It sounds worse than using the on camera mic.

wireless mics as what company?  I find the audio is acceptable. I use a rode wireless go. I do not hear a passing plane or race car scream across the left channel to the right.  its  enough for me to enjoy.

I use a EDUTIGE ETM-001 on two Kayak mounted cams and the quality is pretty darn good.
Sounds better than when I used the same mic with GP H7.

I recorded this on a super windy day with the OSMO actions and above mentioned mics:

Hi, jakemccurdy. Thanks for reaching out! Our apologies to read about the difficulties you're experiencing. We recommend uploading a sample video of the audio issue when you're using an external mic with the Osmo Action and please note what specific external mic was used. Looking forward to your response.