Elektor's Preamplifier 2012 in 2017

Thanks - that helps a lot.
I've made some measurements with ARTA meanwhile and found that I also have a slight 50Hz mains hum in the phono stage. I suspect that my transformer might be just to close to the phono PCB.

Since I don't have any options to rearrange the components, I am thinking about moving the PSU components to an external box entirely.

An external PSU is a good solution, HF interference could be an issue though.
If the transformer is actually too close, you could alternatively put a metal sheet between the two.
 
Is there any sense in making the amp-circuit simpler? Less components = less noise?

Suppose I do not have balanced signals, never adjust bass or treble, and am happy with 2 mono volume-pots so I do not need a balance-pot. What all can be left out?

For treble and bass that is obvious: just leave-out all components that are no longer in the audio path if the tonedefeat switch is activated. (middle circuit)

For the balance this is less obvious: what is the shortest quality-audio path from the input opamp to the volume-pot? Is that as in the 3rd circuit or had I better keep some of those "balance-components" in?
 

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