There are several variations of MSOS I believe even in the first year there were two different boards in the Milwaukee Special. Both had two rheostats that could distort the sound if not adjusted right. But than it is Mighty Sound of Steam so how would you know if the sound is distorted? Being that the system is so old I would think one likely cause of distortion could be a deteriorating speaker.
What I think is interesting about the MPC era and the Mighty Sound of Steam is after the initial offering in the Milwaukee Special, Lionel never seemed interested in improving the system and only took measures to make it cheaper. In 1973 the first tenders had two rheostats for adjusting the sound and also had a pickup roller in the tender so you could operate the whistle independently of the synchronized static. The next generation dropped both of these features and they never returned. The Southern Crescent 1977 and Blue Comet 1978 didn’t even have a whistle. In 1981 (is this the beginning of LTI?) Lionel offered the Chicago & Alton set with diecast tender shell and six wheel trucks and a whistle, they upgraded the system with a downward facing speaker and a grill carved into the chassis for the sound to escape through, which increased the volume. But never put a pickup roller back in the tender so the whistle could be operated independently.
I still like my Cheesy Sound of Steam engines. Out of the nine steam engines running on our toy train display 4 are MSOS, 3 are different variations of Train Sounds one is a PS2 Hiawatha and another is pulling a Williams Tender with the TrueBlast II .
We we have a most unique symphony a sound and the Chicago & Alton is heard above them all. I love it.
I think if I had a high rail layout and not a toy train display I might not be running MSOS. But than I am one cheap SOB so who knows.
