I'll present an opposing view. Yes, it's quite possible to stack the PH180's without damaging the transformers. And yes, Lionel even makes custom cables to do so with the TPC and the PM360. However, I did notice the circuit breakers weren't as effective when they were paralleled. For whatever reason, we had several derailments that cooked wheels and internal wiring without tripping the breakers.
If you're going to do this, I recommend adding a follow-on high quality circuit breaker, perhaps invest in the PSX-AC modules to protect the downstream equipment.
