I really surprise because my subject was about the ATC/P1 amplifier, not the length of my cables.
So, let me precise some little things. I worked in recording business few years, and trust me, 50 Feets of balanced (XLR) cables is a really common things. It's very interesting too see some Audiophile people 'panicked' with this sort for of things. It's really not a problem.
But when you need to have long distance cables you must choose correctly your devices and your cable. I am totally agree with that. The design of my listening room (including the equipment) took me 1 years, and another to build the room. I don't know how many sound engineer built a listen room with 2 helmholtz resonators, but i did ! So trust me, my design is solid.
Now, back to the P1. After 150 hours the sound i now open, deep, with a good soundstage. I am not sure if the sound will continue to change but it seem to be stable. I am really impress by this little amplifier. It's not dry, or difficult to listen. The sound is warm, really quick, and neutral. Woow.
The match with the Audio Note AN-J speakers is perfect.
What about the bass ? The bass is now totally in place. I have a little drop from 125 hz to 20 hz, but with a bookshelf speakers it's normal. I will adjust that with a subwoofer.
My 2 cents