We do have discreet commands for both power on and power off. These commands should work with pretty much any current Zvox. The attached spreadsheet has the Holtek Hex codes, as well as Pronto hex codes. The Pronto hex codes were provided by another installer, we have not tested them with URC remotes.
Current Zvox's will turn on to any IR command that it understands. This feature can be disabled by choosing PS-13 (No Auto On). I would recommend disabling auto on if you are using discrete On and Off commands.