Which speakers to isolate first?

Is your system set up and have you figured out the optimum positions for your speakers and listening seat?

If not, do that first, then work on isolation, diffusion, absorption, diffraction.

If you can access the space, see if you can strengthen the floor. 

Put the subs on springs like Nobsound etc.

@mvanwoert 

I would start with the subs.

At first sight that might seem odd advice because it's known that our ears are far less sensitive to bass distortion than any found in the midrange.

On the other hand in real world terms if you are likely to have audible distortion then it's more likely to be found in the low bass than anywhere else. This is due to the greater movement and work being asked of the drivers and the cabinet.

You should definitely experiment with isolation because going from a concrete to a wooden floor is a fairly dramatic switch in support.

Equipment placed on wooden floors seems to benefit far more from some form of isolation too.

A simple method might be to initially use some cheap foam/rubber under each speaker.

Perhaps some experiment with placement too if your situation allows. I recently watched this video which shed some further light on the complex issue of boundary reflections.

Perhaps it might be of some help to you.

Whichever is more important to you.  midrange is my favorite so I would start there.  The Nobosound spring suggestion is a good one if your speakers aren't too heavy.  Put those on the set that you can't afford to isolate right away and they will help a log for just a little money. 

Jery

Thanks for the input.  Indeed I am in the process of setting up the speaker locations and have a lot of flexibility in placement, but am thinking and planning ahead given the new circumstances.  The Nobosound springs sound interesting, but the speakers and stands weigh about 120 pounds, which I think could be a problem. I'll need to explore a few options.  

I guess CD318 captured my concern that wasn't well articulated, which is that the woofers move more and could be more prone to smearing.  But I guess I won't know until I try.  

CD318 - you didn't include the video link.  

Iso Acoustics makes an isolation foot that will work with your weight.  The Gaia 1 is good up to 220 pounds for a set of 4.

@mvanwoert 

CD318 - you didn't include the video link.  

It seems to display ok on my phone via Firefox.

Oh well let's try again - it's well worth a look at!

Speakers in Rooms - Considerations  for the Best Sound 

Harbeth Audio Ltd  (YouTube)