Rather than just using Dynamat, I added three internal braces, cutting a 1 1/2" dowel from Lowes to fit the internal dimensions, and gluing in place with Titebond, and also drilling and fixing with wood screws. This serves to stop the rather large and somewhat thin particle board cabinet from resonating. You can easily hear the before and after effect by thumping the cabinet with your finger. I also used a little Dynamat where needed on the larger surfaces that weren't close to my braces. I could use a little more on the top and bottom. I used a 12x12" Dynamat sheet per speaker.
Then I stuffed in some Polyfil from Wal Mart, and re-connected the woofer and tweeter. The sound is definitely tight and controlled now. I used half a bag of "quilting" Polyfil per speaker, a single bag was enough for both cabinets for my purposes.
Stage 2, eventually, will be buying a new woofer and tweeter from parts-express.com and adding a high end crossover and thicker internal wiring, and thicker wiring from the amplifier to the speakers, which are now mounted high on a wall, on shelves I built from Lowes shelving board and shelf braces, and sitting on some foam for acousic decoupling. But for now I'm kicking out the jams in style. The stage 1 modified Technics are solid sounding speakers, plain yet tasty, in my medium small sized room. Actually, I might leave them how they are since the bass is so tight and thick! Scour ebay for a pair of these if you will and get to drilling!
