I have used a layer of 3mm high density closed cell foam. Others use all sorts of different coverings. There is lots of info on this forum about baseboards, noise and M track, using the search function will help.

The noise is part of the character of m-track.. What also helps is a good quality (e.g. 18mm dressed pine) base for them to run on.. I used Marco's solution some years ago, but it made the layout too quiet. To each their own I suppose..

Thank you all. The felt option as seen on Martin's forum sounds like a good option. Will look into it.

I run C track now but in my M track days I used to buy foam track bed and cut it to fit. The fewer the screws you put through to the plywood the
better in reducing the sound. The screws transmitt a lot of the noise.

I even cut foam pieces to go into each section. I love M track and have kept all my old stuff. I plan to do another layer above my C track with it if
I live long enough. Got enough troubles with the CS3 and decoder addresses right now so expansion is not an option now.

Eric