Last night, the Mark Levinson preamp was driving me crazy with a high pitch tone (faint but audible) near the transformer side. The noise did not comes from the speakers and after much troubleshooting of powering down all other equipment as well re-positioning did not helps. So, who you gonna call?
FB message William and he immediately told me it might be the LED display causing the high pitched. It’s a DUH-moment, why didnt i think of that! I should have disable the display and voila, no noise!
Another learning from re-positioning the rack to right corner of the room is that is acts like a low pass cut-off filter. It was too much drop of bass for my liking but this confirm that i can use bass trap for bass management.
Marantz CD player do not like to be stack on the pre-amp. It resulted in slight treble harshness.
That is all i spent the day learning audio on the hands-on way, physically.