But is a 7 year old amp worth the time? How reliable are Pioneers?
I have customers using AV receivers at 15-20 years old and Hi-Fi amps at 40 years old. Like Hornetstinger, I'd have no problem with that Pioneer. Or, to put it differently, I'd have massively more faith in that than say buying a 3 year old all-in-one kit along the lines of your Samsung.
No piece of electronics is immune from failure. The general rate of failure for home AV gear is somewhere around 3-4%, but since that's an average it hides some products with higher or lower failure rates.
On the whole, the sort of all-in-one kits such as your Samsung appear to have higher failure rates - usually things such as the optical drive - but I'd put some of that down to them needing cleaning. The problem with all-in-ones is that when one bit does fail there's rarely a way to easily swap out the broken bit for new. A system based on components BD player - amplifier - speaker kit - gives you that interchangeability. Upgradeability too.
There's another factor. This one I think is more significant. It's that all-in-one kits really stretch the budget to cover an awful lot.
The Samsung kit was what, £250-£300 back in 2014/2015? For that you got a BD player, amp, and speakers with all the latest bells and whistles including HD audio, HDMI control, Audio Return Channel, 2D/3D, CD ripping, Wi-Fi connectivity, and a million watts - okay, not quite a million watts, but still a stupidly high number given that the amp consumes probably no more than 200W from the mains socket; and the whole lot wrapped up in a head unit no bigger than the average stand-alone BD player. It seemed like a good deal at the time. You might have even looked at the systems at £150 - £200 and satisfied yourself that you were buying something better; and do you know what, you did nothing wrong. You made what felt like the right decision from the choices available in-store. Who knows, without the benefit of hindsight you'd probably make a similar choice today. Now though, your experience is different.
The Pioneer would have been a £500-ish amp. That sector of the market is very competitive, so the manufacturers have to have their wits about them otherwise the reviews and customer feedback will crucify them. All the receivers in this price category offer a great blend of features and performance, and the 920 is no exception. If you need 4K pass-thru and HDR then this isn't the amp for you. Then again, if £50-£100 is your amp budget then you'll struggle to find alternatives as good sonically and with those extra features for the same money. The only feature it would have been nice to see is ARC, but honestly, that's nit-picking at this price level. Optical works just fine for sound direct from a TV, and with so many AV inputs on the amp then there's really no-longer and excuse for using the TV as a switching hub anyway.
Things to look for in used amps: Ask if he has the remote control; that's important. Check the physical condition. A box and manuals would be nice but not the end of the earth. Also ask if he's had any issues with the amp.
Time is ticking. There are still no bids. Everyone is skint after Christmas. Great time to nail a bargain.