I disagree. A good monoblock should last more like 50 years. A good pair of Marantz 9's are around 45 years old now and still going strong.
Someday somebody will build a really good SSP. Then you will be able to hear what you have been missing. One way to get an idea of the difference is to just compare in stereo. Take the two-channel output of the Ayre DX-5 and run it through a good preamp (either Ayre or tubes is the safest bet). Then compare that against the Oppo and your SSP in two-channel mode.
While you are at it, you can compare the picture quality. The differences here will be more subtle. But for those with the desire for the best, the difference will be worth it.