Picked up a used 16.4.2. Went thru all the pre's, faders etc,...all good there. Tried connecting it to my mid-2010 iMac running OS10.13.6 with a Firewire 400 to 800 cable but not showing up on my mac. Even if I go to " About this mac", "system report" and look under the "Firewire" bus, it shows no devices detected...I will be trying some other cables to eliminate the "Bad Cable" possibility, but if the cable is not the problem, then it's most likely the 16.4.2 Firewire ports not sending a signal...Do you have to have Universal Control installed for the mac to even recognize the device in the Firewire bus? I had UC installed, but un-installed it after I noticed the mac was not "showing" the 16.4.2. on the Firewire bus....What the cost of new PerSonus Firewire Ports?...and are they even available anymore....google search found pretty much nothing..