What is your approach to system fine tuning with cables and cords ?

n80, you never sound like an audiophile, and as such this thread cannot possibly concern you. You simply don't get it.

Nice start, except Erik, he is like a broken record.

I didn't say great, I said "quite good". If it sounds great then you are right - time to build a new system.
Nor did I exactly ask for an advice, I asked about other people's ideas and experience.
Power cords might be first, by the way, especially on the preamp and amp. 
In any case, I am only interested in analog source system.

We can go in all directions. One of them is how you musically match cartridge and speakers. After all, it is the beginning and the end of the signal. Tuning and fine tuning the listening room is a big subject, of course.

Elizabeth, that's certainly tuning, though not what I would call fine tuning. First, you pursue clarity more than anything and this might make it one track tuning. I think, all elements of sonic presentation should be equally addressed, starting with lowest distortion possible and quietest background. Then, you give preference to high frequencies, when in fact one should not differentiate, not to mention that as you know most of the music is in the midrange.
Also, the power cords you were experimenting with are entry level and your speaker cables are about the same or even lower. That's not good enough, you don't hear what your speakers are capable of, in certain areas probably not even close. In other words, it's premature for fine tuning, the system is not ready for that yet.

Elizabeth, I am glad that you get the message.
I will add only this, just in case that I might be right, at least to a degree. Speakers, any speakers, should sing not scream.

Yeah, tuning the room with normal or almost normal items can be rewarding. Unfortunately, there is not much I can do, it is a living room. But I am lucky, acoustics is acceptable, and I mostly listen near field so it’s not a major thing. Putting Purist Dominus on the integrated amp and Purist Aquila on regenerator was. When I reversed it it was still good but much worse. Phono stage doesn’t react that much to different power cords, provided they are all very good. Still does , though, but I am temporarily out of cable funds.