My man cave is the only room we have upstairs and there is no door to it at all, you simply walk up the stairs to the room so no door at the top or bottom and as a result if I really crank movies up, everyone hears it all downstairs so I'm trying to fix that as best I can. Any attempt to remodel and install a door would look really out of place and awful so that's a no go. Someone just suggested to me that I get soundproof or theater curtains to hang over the entrance and so I'd like to do that. Does anyone have any suggestions of a good type or brand of soundproof curtain?

I think you will be disappointed with curtains. Soundproofing is difficult enough when you have doors, nearly impossible if you don't.

But you may be able to reduce the sound to an acceptable level for those downstairs.

Wireless headphones may be your best option for when y'all aren't up there watching a movie or game together.

Without knowing the layout of your house, is it possible to add a door at the base of the stairs?

That's how my current house is configured.

There is no real benefit to any curtain material other than at high frequencies - and even then it would be a marginal difference at best.

One thing you can do though is to improve the sound quality in the room itself with some broadband sound absorbers. These really need to be 4+ inches thick. This would help minimize reflections within the room...but also help keep sound down out of the room as well. 15% surface coverage is a good starting number.

I think after thinking about it, I'm going to have someone install a door at the top at the entrance to the man cave. That should help immensely. I may look into those sound absorbers as well. Thanks for the info!

If you are a DIYer, towels are actually a good sound absorber.

If you get the curtains solved then you're gonna need to work on the sound absorbing rug for the sub.