Both my brothers have room equalization features in their processors and I don't find them very accurate for low frequencies because of the long wavelengths and boundary effects. They do a better job at HF.
My rule of thumb is to measure the distance then add 3ft for every processing step. So for a vented sub located physically 8ft away, I would add 3ft for processing at the receiver and 3ft for processing at the subs DSP chip. If you have an equalizer add yet another 3ft. I have generally found that rule of thumb works well. Occasionally, depending on room acoustics, I will add another 3ft. So for your sub you may want to listen if setting distance from 14-17ft sounds any tighter or louder than at 25ft.
