My CD player in my Shaker 500 quit working and was going to replace with a regular single disc unit, but isn't a Shaker, will this diminish my sound quality. Should I replace with another 500 6-disc changer
If you were happy with the Shaker 500 then I would recommend replacing it with the same unit. They have to be plentiful and cheap to buy from salvage yards.
Just replaced mine for the same reason and I have read this is a common problem. I bought a Kenwood single DIN unit from crutchfield that was a cd player with USB also. Bought a mini 32GB usb flash drive for a bunch of mp3 songs and you can't tell it's on there. They have a wide selection of brands besides Kenwood and other features. Mine cost me about $85-90 shipped and came with everything I needed to install it. Some cheaper units you have to pay for the install kit but it's not much $. If you do go this route, there are 3 plugs in the back of the Shaker 500 and you will only use 2 of them. You can even pay them to build the harness for you but it was not worth it to me because I soldered and heat shrinked everything. They use crimp connectors. The install looks a little intimidating if you haven't wired up anything like this before, but it is really easy as almost every wire on the 2 harnesses you get(1 for the unit and 1 to adapt to the factory harness) color match. You can look at the owners manual online and download it to get a head start before you get the unit. They email some instructions also when you buy the unit for splicing the 2 harnesses together. It looks harder than it really is, even the owners manual. You just have to read through it a few times and it will make sense. When you get the unit, you can use the actual manual to help setup the radio in the car for the sound quality. It will use the amps you have. With a single DIN unit, you will have another storage space under the radio.