Unreproducible problems [solved]

I was listening to a Keith Jarrett concert, in a comfortable chair with headphones, eyes closed, transported, with not a thought to the gear — when I got a very deep hum in one channel. Very strange, I replayed those last 30 seconds of the track — no hum. Then it reoccurred a bit into the next track. I started thinking of the very tedious search for intermittent connections leading to grounding problems. Until I realized the cat was draped across the back of the chair, leaning against the left headphone and purring. [solved]

Then I was going to do one more meticulous comparison of full decode of MQA with the Meridian 818, against Roon unfolding + upsampling without proper rendering, prior to settling the decision of my new headphone rig. Still Dreaming with Joshua Redman and friends, inspired by Old and New Dreams by his father Dewey Redman and friends. I listened to the normal headphone rig without MQA, then switched over to the Meridian feeding a headphone amp — WTF! It had a deep echo, like playing in a church! There is nothing I can imagine that would have that effect. I tried again and again, kept happening. Other MQA albums, kept happening. Then I tried a non-MQA version of Still Dreaming, still church echo. No conceivable explanation. Until my wife, who had been taking a nap, came and requested I play full tracks and not jump around so much, and maybe not so loud? What? Ah, the Meridian had this quirky UX, I had left the speakers on, so I heard both headphones and speakers, and the DSP speakers do some sophisticated processing that introduces a 20 ms delay, combination is like a church. [solved]

Ok, no more gear experimentation.