I can't speak for the Apples Sauce AP, but for the Android software I have tried and trust, UNLESS you are trying to use it as evidence in a court of law, the Android Ap is quite good and representative of what you are hearing. I actually enjoy watching the visual representation of my music and sometimes even learn something about the music from it. I use two different APs,
DecibelX, which gives the most information and
Sound Meter, which is just a basic SPL device and has the capability of being calibrated.