The closer you can get to 60 dB in my opinion the better you will be, so I would definitely try the 54dB setting with the balanced outs if that achieves a total of 60 dB from the phono stage. I used modifed 103R's for about 6-7 years and, in my system, 66 dB would have been too much gain.
I would expect that the difference between 100 and 470 might be subtle with the 470 maybe exhibiting a bit more treble/high frequency energy. Again, try both and see what you prefer.
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