Sound room flooring advice needed

I'm not certain that resonance would be a problem with a floating floor, especially using a dense foam underlayment. But my system has evolved and been tuned while being spiked to the slab, so I don't want some big sonic curveball.

Indeed. I can't say from experience whether you'd have resonance issues or not (though like you I'm inclined to think not). But you're accustomed to speakers which are firmly fixed to an immobile floor. Any compromise there will let the speaker cabinets move, and that softens dynamics and smears each waveform launch.

I've heard this in many setups including early versions of my own. The slightest elasticity beneath a speaker is audible. A floating floor might be preferable in the listening area, but not beneath the speakers.

I had a similar experience but in reverse. I had my system in a second floor apartment and moved to a house where I have a dedicated listening room in the basement with carpets directly on the slab. In the apartment I had to plug the speaker ports to keep the system from sounding too boomy and in the basement I had to remove the plugs to keep it from sounding too thin. From the mids on up the sonic signature was similar, but from the upper bass on down the difference was staggering. There are obvously lots of variables here (although the rooms are similar in size), but the point is if you've got your system sonically where you like it on the slab you might hear something much different on a floating floor.

I'd recommend some kind of moisture barrier and a relatively thick indoor/outdoor (i.e. mold resistant) carpet to avoid using padding in case moisture ever becomes an issue (which, in a basement is not all that unlikely for any number of reasons). If the carpet gets damp or wet you just dry it out and put it back, but padding will have to be replaced. Depends on your situation. Hope this helps and best of luck.

Bill, Zenblaster is spot, I just did this last year and it sounds great. Best of luck...

Wrm57-
I have been involved with residential construction for 30 years and have built dozens of houses on the CT shoreline in the $1m range.
Is this a below grade basement? Are there any existing water issues in this basement or any drainage issues outside the foundation? water is always the biggest concern in a below grade basement.
If you live in Vegas or Az you won't have to worry about moisture but if you do. We use the 2x2 interlocking subfloor that is rubber like on the bottom and a osb on the top. You can put a floating (engineered)floor over this and your speakers will be solid as if they were on the concrete itself. I would mount turntable to stud walls as a matter of best practices.
I have used this product in the past and it's great.
Dricore

Hi Zenblaster,

Thanks a lot for the helpful response. I'm in the SF bay area (near the bay), so it's typically dry for eight months and rainy for four. The heavily-sloped property has no apparent drainage issues. The space itself is more on-grade than below, with no seepage issues; but some of the original linoleum tiles, installed in the mid-1950s, have popped from efflorescence, so moisture has obviously come through the slab at some point.

The Dricore looks like an excellent product, if a little pricey. Do you need to install a separate vapor barrier, like 6 mil plastic, too? Does the engineered hardwood flooring go right on top of it, or is another float layer needed?

Bill