I have the ART Pro Channel version one, probably 10 years old. It's a nice Swiss Army knife preamp - variable hpf, semi para eq with selectable q, optical or tube selectable compressor with nice metering. Plenty of output to drive any poweramp. I wish it had a front panel 1/4 inch input, otherwise it rocks.
I started leaving the pro channel at home to lighten up my rig and ditched the rack altogether, just used a soft mixer bag to bring the crown and cables. I realized if I come out of the sansamp vtdi 1/4 out with the +10 engaged it would hit the crown hard enough.
Even using the zoom ms-60 instead of the vtdi would drive the crown but I needed to switch to the .775 sensitivity and pretty much dime the output of the preamp model on the zoom.
I set the crossover on the crown up for a hpf to tighten up any flab. Great feature. It works well and is easy and light at load in/out time. The best part is the crown is pretty cheap out the door.