I also have the 20S and one of my speakers was blown so I was forced to change them out. I entertained earbuds but found that isn't my thing, I just wanted speakers and I wear earplugs more often than not. Even when the 20S speakers were new I wasn't impressed with them.
I did the ADVRider search and read far too much there and general reviews on other sites. Ultimate I decided on the iASUS XSound 3 High Definition Helmet Speakers. Yes they were $110ish far too costly but I decided that was the route for me. Simple swap and install.
I am beyond pleased and plan on getting the same pair for a second helmet. They put out MUCH more sound than the stock ones did with amazingly better quality and clarity. I don't come close to full volume even when wearing earplugs. They just kickass