For me there is lots of reasons.
1.) Organization I compete in requires you to use a commercially available cd's for state and world finals event. My cd player skips in the dash so I have to use hand held outside of vehicle.
2.) Can not be in the vehicle if it does over 145db and I'm far over that, so yet again must be outside.
3.) Its very consistent using a cd and not using media devices such as USB, Aux, Bluetooth. CD is much cleaner and better signals and there is no delays or lag as such with USB and Bluetooth.
(2015 MECA Street 3 World Champion)
2004 Dodge Ram Single Cab 1500
3 Incriminator Audio Judge 15s
3.25:1 Ratio 4th Order Blowthrough
1 x AA 9.0 TFHE, 2 x AA 150.4
4 X Crossfire XS-M8's, 2 x PRV Tweets