Thats what I said man. ;) The biggest change from demo to master is done through EQ though, especially unwanted frequencies. Most home EQ systems only read frequencies up to 15k, rarely up to 20k. There's a whole bunch of responce still in the higher end of the spectrum. There EQ (and filter) systems cover the entire spectrum, so whatever was not covered in the mixdown stage is fixed by the master engineer. The fattness, clarity, and volume is relative to the attention on EQ. Plus with the added acoustic environment they preform in, they are able to treat these frequencies, which are the cause of the wooly sounding demo, much more precisely.