2 speakers is legal.Oh, and one speaker or two? And if two, and playing tunes, you still feel situational aware? And I assume that is illegal since two ear buds in while driving a car is illegal.
I installed a pair in a helmet years ago, and tried listening to music a couple of times. Having it loud enough to hear over my ear plugs & wind noise made my ears ring, and I stopped.
Maybe on a bike with a big screen.
I've considered riding with noise blocking ear buds to listen to music. Using two isn't legal. Haven't tried either 1 or 2 though. Can you use those instead of speakers for the Cardo?
Might try a ride with a single earbud and see. My music app will do a mono mix.