You can get to the grommet from the front of the car, but it is worthwhile removing the centre console to remove the glovebox, then you can cut that little sneaky T**T of a bracket off so that if you need to access behind the dash in future, you can just pop the glovebox out.
Plus you can then do a tidy job and cable tie all your audio cables up to keep them neat.
Also, it is nigh on impossible to fish for the power cable once you have pushed it through the front.