Hi Phoenixrae
I'm glad you found the information in those threads helpful. Actually the idea of four EP subs was not to have "louder" bass but smoother linear bass across all the seats in my home theatre and it certainly achieved that objective. Whether I have one or four subs the volume is set at the same 75db. Most rooms benefit from multiple subs in reducing room nodes and better FR.
All four subs combined were calibrated at the same 75db as each of my other speakers. Because of bass reinforcement that meant I could calibrate each sub to around 65db for an effortless sound. I am now down to two vertical ep600s and an SMS-1, with each sub calibrated at 70db. 2 subs closely collocated produces an additional 6db in output, while 3 subs creates 9db and 4 subs 12db depending on placement. Besides better in-room frequency linearity, compression artifacts are virtually eliminated and distortion is kept at an absolute minimum with multiple subs. Adding another sub is one of the best ways to improve the quality of bass reproduction and sound quality in an HT.
