Is it worth replacing an old amp?


Let me first apologize if this question has been asked before, I sure it has. I have an old 5.1 setup, Linn AV 5140 and 5120 speakers along with an old Yamaha DSP-A1 amp. The newest equipment I have is an OPPO 205. All my music is digital, where the vast majority being Hi-Res flac and dsf. The question I have is, would I get a noticeable increase in audio quality if I was to replace the old DSP-A1 with lets say a used Mcintosh MC205 or comparable?
divby0
Although you don't know until you try, you'll find that most mass market receivers are pretty bloody awful. Artemus has it right. 
It all depends on the match between the amp and the speakers it could be better or worse, it is always a question until you try it and listen to the change whether good or bad.
I've been using an old Aragon 8008BB for the past 25 years in my secondary system with some KEF LS50s. I got the bug to upgrade, so I bought a PS Audio Stellar S300 Class D amp a few weeks ago at a great used price.  Bottom line ..the S300 does some things better than the Aragon, but overall, the Aragon is richer sounding & more musical. 
The latest Yamaha models are very musical with a European flavour rather than the historical Japanese sound. The HT models can do Stereo very well and for their cost and reliability (which you are aware about with your current amp) but the dedicated HiFi models sound fantastic for the price.
All IMHO 😷

AG 🇦🇺