I also used 2 layers of snow blanket on my xmas layout and it helps i ve tested carpet padding on my layout with some of the track on the foam board and some on the carpet padding and the difference is night and day.
Carpet noise fastrack.
Fastrack will never be the quietest track but you can do things to help with the noise level.
I ve run fastrack on carpeting and it s queiter but to me carpet still lets the sound to escape from under the track.
In most cases you need to use an underlayment specifically designed for noise reduction between the carpet and the standard pad.
Finally rather than putting fastrack right on top of a wooden table put a layer of homasote in between the track and the table.
To eliminate all noise look for a rating that is 75 or higher.
Homasote absorbs much of the sound that gets through the carpet padding.