Would integrating a subwoofer be best done with an RTA or with an SPL meter? Wouldn't using a RTA be a better alternative than using a SPL meter? On the RTA, we can see how smooth the mains cross over to the sub. Any differences can be seen clearly in terms of stair-stepping or obvious difference in SPL at before and after 80hz cross-over point. SPL meters don't do this and results very dependent on the accuracy of the meter at lower frequencies. SPL meter method would be more like an assumption method since room modes and resonances would throw the accuracy off, which otherwise RTAs can detect. So, isn't calibrating speaker and sub levels be better on the RTA? Or am I missing something?