You’re right, it is all relative and, as some of us have found, there’s enormous untapped potential in a 552/500 system that is liberated with Music.
As far as the M6 is concerned though, I wouldn’t want anyone to think that a Music mains lead is obligatory. I was delighted with mine when I heard it initially with an Epic cable but found it simply got better and better as the mains lead improved (and Music was admittedly a bit of a “wow” moment).
Agreed 
After three weeks listening,my Chord music into M6 block is really a magic…all my disappointment and weakness I had before vanished,best upgrade I ever had
If you can try one on your 552. 
Do you mean adding another M6 only for 552?
Now that you have decided that you really like what a Music mains cable adds to your system adding another then another etc will improve the sound even more.
This will cost a fortune…two M6 and another chord music cable……it’s a madness decision.
no not another M6. I’m afraid you aren’t translating well Meni. I speak fluent Spanish but not French sadly
Maybe I didn’t follow you good ,please explain again…English isn’t my native language
I know.
It’s a simple suggestion and judgment.
You could try another Music mains cable from your 552 to the M6 block if funds permit it.
You mean instead of my power line music from 552 to M6?
Yes
Wow…if so,full music loom will lift much higher
@Meni , sell your car and buy a bike. Then buy 2 Chord Music for each of your 555 dr, and one for the 500 ps, and finally 552. And don’t forget the chord music lan cable. 
Of course but that would be very expensive. One to the pre amp next is worth trying.
Thank you I need to wait a while
It’s an endless hobby
Do you still have 2 kidneys ? 
The Chord Music is near 2 months salary for me. Fortunately I can access easily to bank credits, at low pourcentage. I see an N555/555 dr and Chord M6 in my crystal. Very probably final step for me.
I’m afraid I have to agree with this