The old MiniAmp series pictured suffered from plastic deterioration over time. Sound great at first then every one I knew fell apart — from the internal heat is my guess.
Mine is in A1 physical condition, works a treat, isn't noisier than others I tried, and does what I need. For several years it lived in a rack of gear but is now on the front left of my mix desk. No interference other than the RFI & EMI that my entire house suffers.
Perhaps I'm lucky.
I don't replace stuff until it's no longer fit for purpose.