Graphene spray and ...

Graphene in by itself is highly limited but when combined with others, its enhancements become notable. In the case of the carbon fiber for the driver, its more likely to be added to the resin solution used in the forming cone and fills in gaps in which remaining resin would typically remain. My expectation is the stiffer cone aided in pushing the cone breakup a bit further out.

The issue that remains crucial with graphene is methods of its application. A few years of experimentation were required to optimize the application of graphene to improve rubber products such as tires and shoe soles. In rubber tires, it resulted in improved strength in the rubber without reducing other performance areas like compound grip. In some respects, it improved grip performance as the lattice aided in maintaining is structural shape of the tread pattern under load. This is often called tread squirm. 

BAC's wheels used on their Mono race car and some experimental bike frames achieved a 20% reduction in overall mass without loss of overall modulus of the finished product. You might even see its application in cabinets construction that use composite materials at some point.

This in addition to the broadened use of pitch based carbon fiber still leaves some development to take place in material science.  

With manufactures expressing that success with graphene is very dependent on application, some time and experimentation will likely be required.

It may have a benefit in speaker driver surrounds as its structure in rubber aid in rebound. We've also seen carbon epoxy implementations that may add to driver diaphragms that are carbon composite. Likely reduction in distortion and further frequency response range before breakup. Some speaker cabinets may benefit with its application.

It was thought that graphene could be use in voice coil as yarn had been recently developed, but now that stanene outed as graphene's tin derived cousin and it shows now resistance at all until 100C, it may become bypassed as a conductor.

The Mat-Sci lab is going to be an interesting place be and I have little doubt some will end up in audio products at some point. Might be a bit until affordability makes it more than just a lab experiment though.