tommohawk if you were referring to putting a sub in 'the middle' being the middle of the room, you are asking for major disappointment.

Subwoofers are designed to couple into the standing mode shapes of a room. The way that you do that is to put them in a location where they will couple with the most modes - that is in corners. Put it in the middle and you'll have nothing but disappointment.

I agree with shockwave's comments and again stand by my comments that there is a reason that there's a difference between PA speakers which are designed for listening in the far field at higher volumes, and nearfield monitors which are designed for use in the nearfield at lower volumes. Already typed it out many responses ago.

And Mac I flat out got what you did as well - but perhaps you didn't even mean it that way!

For practicing - your concentration should be on practicing not critical listening. If you want volume go get a used crummy little practice guitar amp and some adapters and cables to get the signal into it. It will blow you out of the room with volume and you'll hear all the timing and pitch cues that you will ever need to practice along with music. Don't spend more than 50$ for one from eBay, or even a crummy old shelf stereo system at your local Oxfam store. Then spend your money on some nice nearfield monitors.

-Scott