Welcome to the Gauge Bill:
I agree on using foam over the plywood. Whether you use the foam or not though, I would suggest applying latex adhesive caulk along the bottom of the molded roadbed edges. This will help hold the track down and should cut some of the sound transmission down. I've never used the B-Mann EZ track, but I have looked at it. The caulk is pretty inexpensive and should work well for you. Let us know how you make out.
Eric