Finally calibrated my system to 75db with the test tones and an SPL meter (then added a couple of db's to the sub! ) and oh my god what an improvement, I had the rears about 4db too high and the centre a touch low and the sub WAY too high. Now everything sounds sooo much sweeter, I'm chuffed to bits and wish I'd bitten the bullet and bought an SPL meter sooner, hard to justify £30 for something that only gets used a couple of times though. So the point of this thread, well just as the title says, if like me you wondered how much use it would really be, beg, borrow or steal (well maybe not steal) one and give it a try! Xmas day at my house, wonder how the family will take to a bit of movie watching at reference after dinner!