I haven't tried a single pro485 but have had one 485 and two 6.5" Kenwoods that come offered with Supras and Moombas. This setup is extremely loud. One Pro485 would send out plenty of sound also. Much better than the average pair of speakers because of their EFG cones and HLCD.
Not intentionally but every now and then I find that one of the plugs is not making connection and only one speaker is playing. My amp is rated at 400 watts to each Pro485. I would say that one Pro485 is definately adequate for reasonable riding listening.