What the internal DSP in the Apollo allows you to do is run the UA plugins within the Apollo itself, so you can dial in a great sound in the UA Console, and then in real time simultaneously use the plugin while printing it. Doing a vocal track? Dial in a preamp plugin like it was a piece of hardware and record your take with it with zero latency. It's not so much about using a plugin, but being able to use a plugin that acts and responds like a piece of hardware would.