Here's the graph of the room response from Lowrider's room. It has several lines, each represents the response after a certain elapsed time. The first (blue) line is the immediate response (0ms) which is almost completely flat. The other lines show how the response changes in 80ms intervals, as the sound 'decays' to silence. Generally, during decay, peaks and valleys just get bigger and bigger as time passes. It's the result of the sound reflecting around the room until it's quiet. The only way to keep a flat line through decay is to have an anechoic chamber! I have to say that I find the result surprising because even rooms with expensive acoustic treatments rarely have such a good response. However, below 200Hz it, two subwoofers certainly can make a huge difference (much more than one). Even TacT say their equipment only really works properly with two subs! Another possibility is that I don't know how to interpret the results properly . Anyway, what you need is the ETF5 software from http://www.acoustisoft.com/ - you can download a free trial version which has some limitations (you can't save files). Then you need a laptop with a soundcard. If possible, a 'full duplex' sound card which means it can 'record' and output at the same time. For a microphone you need an SPL meter - I ordered mine from http://www.cornwallelectronics.com/ and it cost GBP 40. Then since most sound cards have 3.5mm sockets for microphone and line out you need two 3.5mm jack to 2x phono leads which I got from Dimofel. The "Radio Shack" SPL meter has a single phono output which I connected to the 2x phono plugs of the lead going to the "line in" of my sound card using a 2 into 1 "Y" phono splitter which I also got from Dimofel. Michael.