Paul:

1. I assume that in referring to Nashville, do you mean the TV series?

2. Are you mixing over speakers in your new room? If so, no amount of Izotope or other processing is going to help overcome the very strong room modes that you very likely have present in that room due to the quite narrow shape and concrete walls.

I realize that most people will say to never mix over headphones. That is generally true; particularly for stereo imaging. However, for very narrow and/or small rooms, there is almost no way to actually compensate for the undamped room modes you have right in the middle of bass guitar frequencies.

You can test for the actual modes with a little bit of a complicated setup if you have a microphone and a way to record output of your monitor speakers while keeping it from feeding back into the system.

The reason you might need this is to record how strong your room modes actually are and what kind of compensation you will need to do in an output bus EQ so that when you do mix, you aren't compensating with individual track EQ.

This is what automated systems like the JBL MSC1 system does.
http://www.jblpro.com/www/products/vintage/vintage-recording-broadcast/msc1#.WWQf1VGQwdU

and IK Multimedia's ARC systems
http://www.ikmultimedia.com/products/arc2/

These are automated systems. However, you can accomplish similar results for strongly undamped modes like what is probably in your room, by using a sine sweep waveform played through your system, and a microphone at your listening position, recording the output of the speakers.

You record the signal and then look to see at what frequencies you have strong modes - this is where the recorded signal will go significantly higher than the rest of the signal. Several ways to go about measuring this.

However, before going on - do you have interest in the topic?

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