Really enjoyed that video of your layout John!
I'm getting there with every motive power lashup that runs on mine having sound.
Yup, the air-tight speaker enclosures and larger-oval speakers DO make a huge difference in the quality of sound.
I really like the progress on your layout and can't wait to see it with grade-crossing signs, signals, fences, telegraph, telephone and power poles, big lighting towers in the yard, more period vehicles and populated with 1:160th humans!

Cheerio!
Bob Gilmore