I have a Pioneer SX-780 that was blowing a main fuse (#4 - 4A I believe). I removed the power wires going to the Darlington outputs, replaced the fuse and the unit powered on and lit up AND the speaker relay clicks. Great, right? So, I went to eBay and bought some replacement STK-0050's ($15 each). These weren't the cheapest ones so I figured I had a better chance of getting genuine parts. I touched up several solder joints on the voltage regulators since I knew it's an issue with these units. I seem to have all voltages properly. I replaced the bad STK's with the new ones from eBay, the unit now powers on WITH the STK's wired, fuse doesn't blow, but I have no sound, headphones or speakers, and NO speaker relay clicking. I can remove the power going to the new Darlingtons, turn it on, and the speaker relay engages and I CAN get sound out of the headphone jack, although it doesn't sound good, kinda distorted sounding. I'm at a loss. Do you think I got a bad/counterfeit pair of STK-0050's??? Thanks!