In regard to the Zu Omen Dirty weekend, the Clarity cap upgrade is a must as far as I'm concerned. I'd also look into the snubbing resistor option. It smooths the impedance curve and lowers nominal impedance to roughly 8 ohms. The rubber footers are a nice option, but that would depend on the type of floor you have. I use them on a tile over concrete floor. The cap option is the only tweak mentioned that requires a bit of skill and patience as you have remove the drivers to make the change. I would call them direct as the cap upgrade is no longer mentioned at their site. I'm sure they could give you the cap values and manufacturer options if they no longer offer this upgrade.
