Recently I bought a new Lionel TPC but found the Lionel TPC would not work with an old pre-Lionel TPC and a dz2001 data driver (See my earlier Forum thread (11/19/11.)
A fellow club member Chuck (cjack) built an amplifier that is plugged into the serial output of the Legacy base. He indicated that generally a dozen TPCs and other data using devices such as the dz2001 can be driven reliably with it. We installed his amplifier on Friday and it appears to solve my problems. TPCs and switch machines that were not working or working intermittently are now working!
Chuck explained to me that the output of the new legacy command base was lowered from that of the earlier TMCC base and would not drive data through the old TPC, the dz 2001, and the new Lionel TPC at the same time. In fact, its output would drive only a few, less demanding devices. Based on this,it appears that strong, precise data was not consistently reaching my TPCs and or my dz2500s since I installed Legacy in 2008!
In hindsight, I could kick my backside for not realizing that my problems arose shortly after I installed Legacy. But the intermittent nature of the problems combined with things working fine when I removed the dz2001 fuzzed things up!