This is actually the unfortunate story of an SX-5590. Quickly established the L channel main outputs were shorted. When these shorted transistors were removed, it would come out of protection (two clicks) but no tuner or panel lights. Went through the stabilizer board first, and found three failed transistors, as well as a failed zener diode and several caps either failed or out of spec. All were replaced (including all E-caps) per parts list found here on AK. As long as I was in there, I pulled the protection board and recapped that also even though that appeared to be working. Next, I turned to the failed L channel amp. Checked each transistor off the board. Surprisingly, found all good. Replaced all E-caps on both amps boards anyway. Obtained two pairs of new NEC outputs (more on this below), cleaned board pins, reassembled everything. Using a DBT w/100w, gave it power - and it lit up, FM tuner came to life. Removed from DBT, set stabilizer voltage to 65, perfect. Set amps per manual, all dialed in without a hitch. Used 65mV rather than the 100 specified, as it seems this is recommended after researching here. Finally hooked up speakers, and with some cautious optimism, gave it a bit of volume. Sound on both channels but - momentarily I heard a pop from the L channel area, minor puff of smoke, and of course, sound ceased. Crap. Removed the four outputs, all failed. Powered up (w/ DBT), and the R channel seems okay. Here's the question. Will counterfeit transistors fail easily? Thing is, I got them from eBay, and though marked NEC, who knows? I thought I'd done due diligence on the amp board, but there's likely a problem I didn't catch. Help! Where do I go from here? Thanks for any help.