No wonder. In a standard gaming board's low profile assembly, anything between the pcb and lower case isn't going to impact sound much with there being so little empty space, the bottom basically wraps around. You're basically just hearing the switches, metal switchplate and keycaps. The other keyboard is roomier, thus there is some echoing in the bottom case to be dampened. Guess you don't really need to put much consideration into this type of mod though, it's quick and easily reversible. I think the M71 sounded a bit better before tape, it constricts it too much, but it's all a matter of taste.
