I'm using signalscope pro to generate the white noise and it's that which I am asking about.
The output from my iPhone is going out of the headphone socket into an amp and out to a two wharfedale 9.1 left/right speakers and an sw150 subwoofer.
I feel like the white noise output is not across all frequencies because if I send a similar db level in a single tone out to the speakers and take the frequency down to the sub's level, it generates a lot of movement in the cone which is not replicated in white noise mode at the same db level.
I know it's not very scientific but it just feels wrong.
Thanks for your response,