Self's multiple balanced input CMRR - Any adjustment trimpot?

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Dear all,

I am building a multiple balanced input similar to the self's examples in ordert to implement it in pro audio equipment. My main requirements for this stage are:

Noise: -115 dBu or better (20-22Khz BW)
CMRR: -70 dB or better @ 1K

I have the following questions:
-Have anybody measured the CMRR of any these multiple arrangements?
-I am wondering how to and where to place a trimpot in the multiple arrangement as shown in picture 1. Is that posible for a quad or higher arrangement as the one in picture 2?
-I might place a trimpot in each differential amp, but it will be hard to calibrate for minimum CMRR. Am I right? Any idea of how to calibrate multiple configuratios?

Kind regards to all!

https://drive.google.com/open?id=0BwuLkRyHmt7jcTM5U05EdW1wdWM - Picture 1

https://drive.google.com/open?id=0BwuLkRyHmt7jWHczM0lKWG00YXM - Picture 2
 
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