Different Greenback Sounds
The 20W Heritage sounds sweeter and tips over into the overtones earlier, while the 25W sounds drier and more woody.
Heritage 30W 75Hz: Loud! Powerful upper mids, defined bass and clear treble. Great for classic rock, hard rock etc.
Heritage 30W 55Hz: Loud! Deep bass, yet focused, tight mids, slightly rounder highs than the 75Hz but still very transparent.