I have spent last few days reading up on all past posts and on your recomendation bought a SPL meter from Corwall Elec You were right NEXT DAY!! service was ace. Used it last night and set speakers up to 75db including sub (is this right?) it sounded right, I didn't think it sounded too bad to start with but wow what a difference!! I have mission cinema 6 connected to sony str475 via TOSLINK. Speakers set to small and crossover on amp to 150hz (its amazing what you can learn on these forums) The problem is the sub on some dvds on the rock dts in particular it makes a high pitched squeekor whistle out off the hole (sort of vibrations) on the back of the sub when playing really high LFE scenes. I put a sock in the back which stoped it but was worried it may break my sub. If it is not already broken! I am using those cheap red and white freebie leads which can't help, but will upgrade soon. I would like to know if blocking the reflex port with a sock would harm the sub or effect the sound and if so are there any other solutions.