I've got a Penta, but my setup is a little different. I run the digital out into an Event EZBus and then send the signal via USB into my computer, so I don't really run through an internal audio card .
I'll try and cut some tracks later running out of the Penta via the analog outs into my EZBus and let you know if I can hear a difference in the AD conversion between the two units. That might give some info of how it would stack up.
I’m using an RME Audio Digi 96/8 PAD and to my ear the AD converters on the Focusrite are just as good, plus, using an S/PDIF out I don’t have to worry about ground loops etc