The correlation that he is speaking of is like this:
If you are spiking on your master out it will apply a limiter to the sound before it goes through the recorder…Once it hits the recorder it will Up the dB based on the gain on the recorder. The way i have understood Traktor recording works like this:
Sounds goes from channel A through the limiter/gain then into the master then it is run into the limiter again, then from master to Recorder.
This is all a digital process too so as oppose to just cutting down the dB like you would using the trim on a analog mixer it is compressing the sound to lower the dB…the problem with this is that with songs that may have been mastered a bit off is that compressing will even out all your frequencies, oppose to just lowering the dB levels. This is why you are getting “muddier” sounds, as often the limiter will dull out the really high frequenices and boost the mids.
More about compression:
http://en.wikipedia.org/wiki/Dynamic_range_compression
Try recording a mix with Headroom 0db, Limiter off, and have your master at around -10db. Then adjust your recording gain to just under the red and see how it works.