I have a Sony STR-DA4ES which has seen a lot of use since it was put into service in 2003. In that nearly 15 years of service, it saw 3 years of storage in a controlled environment (in box, in monitored basement room with dehumidifier). After its move out into the new digs, I hooked it up to the rest of the 5-speaker system it had been mated to for years: 2 Athena AS-F2 fronts Athena AS-C1 center 2 Cambridge SoundWorks Surrounds Sony Bravia KDL-52XBR9 HDTV Sony DVP-NC600 DVD disc changer Sony BDP-S1 blu-ray player Wii And the newest component (since the 2016 move) ChannelMaster DVR+ After being freed from its box the system was left set up, plugged in for a day or more before being turned on. All of these components were plugged into another new component, a CyberPower CP500PFCLCD uninterruptible power supply (known for its smooth sine wave power). Its twin was already proven on the PC/office equipment. In the end of the first day of tweaking and balancing of the speakers, I had it turned up to near, but certainly below reference level and it went into auto-protection safety shutoff and became eerily dead. This was a once only event. Not long after the reset (days), it began exhibiting a sporadic popping sound from the speakers (L,R,C,LS,RS). After consulting a different forum (now largely inactive), further diagnostics were done, below are the questions with my answers: Does the front panel display flicker? Never has. Are digital & analogue inputs affected? Yes, optical, coax, RCA, even the built-in tuner. All are affected. Are video signals affected? Not so far. Do you have another amp to test if the pre-outs are affected? I'm afraid not. I have not noticed any popping from headphones in some brief testing. More testing of that may be in order. One sage of the forum suggested: [There] is the possibility that the electrolytic capacitors in your 14 year old DA4ES could possibly have something to do with the popping that your Receiver has been experiencing and that the caps may now need some extended operating time to fully form…. I… wonder if leaving the DA4ES powered up continually for several days might help with the problem? It did, it really did! There was very occasional popping on the left side though it is unclear if it surround or main or both. That was 2016 and 2017. Now in 2018 the left front main has gone silent. It was working, then just stopped. Turned off the receiver allowing it to cool a while and turned it back on, then silent after a couple of minutes. Now it the left never comes to life. Heard a loud pop out of the right side the last time I used the system… I’ve not wanted to turn it back on since. Details: so the left channel in headphones is affected, the left front main channel is the only one affected in all other listening modes. Center and left surround are fine. Both right front main and right surround are fine. I believe the aforementioned popping may have been in the left front main (and I thought, though was never certain it was also in the left surround). I have used tuner, blu-ray direct playback (so it's affecting the pass-through), and optical. I may turn it on again and it will be fine like it did a couple of times. Tonight—nothing. I expect that costs to repair, if I could even find a repair shop that would even work on something this old are likely not worth the expense. Any thoughts or suggestions to toward a possible diagnosis or resolution? Or is she dead?