Wayne mentioned the lower mids, and thats just it. It seems like everytime I have to add eq to a kick drum track it's the mids. I find it mostly from 250-1000 Hz. I used to never associate this range with this instrument, but try it. Put a song with a snappy(but not clicky) bass drum sound(I like "Home at Last"[Steely Dan - Aja]) in your Windows Media Player and turn the EQ's 250-1K range all the way down. Sure you still hear the drum, but the toe tappin' snap is gone. I realize cabinet colorations are a lot more subtle, but we're going for frequency range demonstation here.

Thomas