This is all very disappointing but mirrors my experience with Mark Levinson lately as well. I bought new 523 and pair of 536s a couple of years back and went through 3 different 523s and never got one that worked. My local dealer allowed me to trade up to No52 Ref which worked perfectly but I finally sold and went to tube preamp. One of the 536 monos had an issue with the front led and they swapped it out and those have been good ever since. I have had two more friends buy the same 536s from same dealer recently and they experienced led issue as well. ML seems to really be struggling with quality across the board and their customer service seems to always blame the customer first. When I finally upgrade my amps to something better ... I’ll be done with Mark Levinson for good which is a shame as their new amps,preamps, and Integrated amps are really very good sounding.
George
George