Schuberth E2 with Sena SC2 - too quiet

Hi there, I hope this is the right sub to post this question.

I have been using my E2 for a while now and am generally satisfied. However, the communication system is always much too quiet (SC2). Music or audiobooks are very quiet, and phone calls are not possible because I can barely hear the other side.

I have tried the following configurations (Motorcycle: BMW F750GS | Phone: iPhone 13):

• Helmet connected to motorcycle | Phone connected to motorcycle
• Helmet connected to phone without motorcycle
• Latest software updates for the SC2
• Ensured that the phone's volume is set to maximum
• Ensured that the SC2 is set to full volume (Remote buttons)

Any expirience from you guys or tips I could try to solve this?