Slightly out of date question. Does anyone know if there are different versions of the db1 gold? The version I have has the twenty21 woofer. I'm now paranoid it doesn't really match the other 5 db1+ I have. The product images generally don't have this woofer. But maybe that is what this is, the old+tweeter and the new, at the time, 21 woofer. I thought it was just the + tweaked slightly, not a different driver. Are there any scientific tests to show performance?