I have the latest Shoei helmet and latest SRL2 unit (Aug 2020) with firmware up to date. Audio volume at city speeds is OK (even have to turn the volume down a bit) but nowhere near loud enough at highway speeds +90Kmh with earplugs in.
Sena has done a great job with the functions and features of the SRL2 base unit but all to no avail if you can't hear anything.
As a suggestion, can Sena add another audio setting (Earplugs Only) for those that choose to protect their hearing by using earplugs when high-speed riding? The user can always turn the volume down if needed to suit the riding conditions. My Aldi unit was louder (and much much cheaper) but lacked any features hence the upgrade.
I would be interested to hear other opinions.