Sound room flooring advice needed

The good news is that any water issues would have shown up long ago. That said, I would treat the floor as though it was a shower base. They have a waterproofing that comes in a 5 gal buck and you roll it on, as waterproof as a swimming pool when it dries. Make sure your concrete floor is relatively flat and clean. Roll this stuff a few inches up the walls and you are ready to go with the Dricore.
There are several companies that make similar products to Dricore and I would check them also to get the best for what you need.
You can contact me by email if you have any questions that might not pertain to this thread.
Good luck with your project, do it right the first time.

are you talking about a swimming pool? I remember when I built my listening room as a separate building deep into the earth my wife claimed it would have been better if I had decided going for a swimming pool.
Nevertheless when you have the chance to build it up I would go for a good concret basement, some layers of isolation treatment, then a wooden floor of heavy large pieces at least 40 mm thick. On top of that I would work with carpets and isolation treatments again as you are already doing. Don't forget a proper treatment of the walls and the ceiling. This is such crucial. It is not only the floor. The waves have to be vaporated at the side walls and also look for proper reflections of the different frequences coming from the ceiling in front of your listening chair. This is very important for the real good sound you are going for. Good luck, too.

Great info, Zenblaster. After the Dricore is down, you're talking about floating the floor on top of it, right, not gluing? If floating, what kind of underlayment do you recommend between it and the flooring? I've considered cork, PE foam, and a product called Quiet Walk. What do you think?

Pops, I looked at your system page. Your floor is gorgeous. Looks to be birch, which is what I'm planning to use. Did you float it on top of the Dricore?

The engineered flooring will come with a padding that you can lay right over the Dricore. Lock all the flooring together leaving a little short all the way around for expansion.
Do all your walls and ceilings first, right down to the finished paint.
Install finish floor.
Install base trim and shoe mould to cover the expansion gap.
Enjoy for years.

I used a floating cork floor in the basement. It sounds great and cork is very resistant to moisture.