 
Other than that, +1 to the letter to what you said about the application before. There's great insight.
ISO panels are all about reducing mic bleed and other unwanted aural attributes. Depending on material and placement they can be a decisive force / improvement in your recordings.
If your room has hard material walls the sound will bounce a lot and it will be present in all the mics, too. You can reduce this by adding soft materials to the walls that absorb waves. Don't need to buy arbitary stuff. Maybe a simple thick curtain on 2 out of 4 walls that you can pull when you don't record can bring a drastical improvement, without investing an ample of money.