I have a pair of MC501 monoblocs running my 3.6 Maggie’s. I bought them used 15 years ago for 6K. I could sell them tomorrow for 6K. I will probably never sell them, but try that with any other brand amplifier.
The reason the hold there value is that they are quality products that last a long time and have a following (and NO they are not all sheep).
I ran through a few amps before finding my 501s and they make my Maggie’s sing.
And to complete the circle, I have a C220 tube preamp bought about the same time that still sounds great and is worth more than I paid for it. I just took a Ms300 music server out of my system that was still working to go to all streaming, but 15 years out of a computer based product is amazing. FYI, my new MB20 works seamlessly with my iPad and iPhone.