Uneven speaker wire length
I recently measured my home theater speakers with my SPL meter and receiver's test tone and found something interesting...all my front speakers have the same wire length(15 feet) and their SPL matched up, my left surround speaker have 23 feet and my right surround speaker has 32 feet, but their SPL didn't match up with neither the front channels or each other. The left surround is set at -3dB and the right surround is set at 0dB to maintain even SPL with all five speakers, my speakers are all idenical(JBL N24) except the center channel(N-Center), which is 4dB louder but I also adjusted accordingly. I'm ruling out the possibility of speaker defects and receiver malfunction b/c I've noticed this problem ever since I had this setup(with the same 12 guage Sound King speaker wire), so is uneven speaker length taxing my power?
I've also heard about uneven speaker wire length can cause phase shift???