Heya, I don't have the Ox anymore, but I have a Friedman IR-X and I really love it. I use a 1/4 to XLR adapter to connect it to my Apollo's mic preamp. It seems to work fine connected to the Hi-Z or LINE inputs as well, but Dave Friedman himself said it was designed to be plugged into a mic preamp.
While the "dynamic speaker emulation" of the Ox is a neat thing, I've found several other solutions that sound great to me without using Ox or Ox Stomp, obviously just loading a good IR (the ones that come in it are good, the Creamback is my personal favorite), I've also used a few plugins in the DAW which impart no latency such as Softube Celestion Speaker Shaper and Cabinetron (with the cab sim turned off on the IR-X)
But really, what makes the most difference IMO is a good room sound. I just use a stock Impulse Response loader in REAPER with a room IR and I'm very satisfied with my Tone. Of course the UAD Reverbs and other plugins are great too.