I am a Newbee
I am running Legacy 990
I want to add the Superbass PB to the Alco PA AA set.
Do I add it as a second unit on a consist or do I add it along with the AA set?
I have a similar set-up with my Santa Fe F-3s with Superbass B unit. I made mine a lash-up and put it behind the lead A unit. I also set them up for "Train Link". When you do that you can access the cars in the lash-up and turn sounds on and off in each car. The bass will have great sound and a great horn. Fun to experiment. The Superbass is worth it.
I'm jealous. I am awaiting my dealer to get my NYC set in, so I can experience the fun you must be having with this new set in your hands. Having it is perfect for Memorial Day weekend, unless your going camping