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
Simple answer.   Audition in your system a 'better amp' you may wish to purchase.  Any dealer worth his salt will allow you to do that.
If he doesn't, walk away.

If you think the sound quality is better enough to buy it, then buy it.
From the dealer.  Don't be a cheapskate and buy the amp cheaper on the net.
@divby0 some speakers are easier to drive than others. In that situation, an amplifier that sounds good with an easy-to-drive speaker may have problems with a difficult-to-drive speaker and therefore will sound bad.

Likewise, there is a degree of matching that will take place. Let's say you have a speaker that has harsh treble. Using an amplifier that rolls off the high frequencies could make that speaker sound better. But that same amplifier with a speaker with smooth extended treble will make it sound like you're missing out on some of the music.

As others have said, you need to go listen to some amplifiers to decide if it will improve on the sound of your existing system. Just as what you hear when replacing your amplifier will depend on the rest of the equipment you are using, plus your room and listening situation, later on if you decide to replace something else like your speakers, the result will again depend on everything else including the new amplifier you got.
Hello,
If your amp is working you will notice a much bigger difference in the preamp. Emotiva has a two channel preamp with HT bypass. Used it’s about $800. This is the start or bottom of preamps but has awesome sound and capabilities. On the high end but doing the same is Ayre or Hegel. I think MACs have this feature too. Try to borrow a two channel preamp so you can hear what I am talking about. I do this right now with the Emotiva ups1 preamp with a Marsh Sound Design. I would pass on Rogue Audio with bypass. When I tried their HT bypass it had a 10db loss in volume due to you power it off to engage the bypass. This store in the Chicagoland area lets you try before you buy. https://holmaudio.com/
They do not carry Emotiva so you will have to trust me it’s awesome with tons of different amps. I hope this helped. 
Divvy,

I too had a 205. When I went to Streaming i sold it and bought a DAC and a Streamer. Now talk about an improvement in SQ! Wow, even the wife commented how much better it sounded. And that was using a $750 Ares 2 DAC. 

Not sure how much you want to spend.

I have no experience with 5.1 receivers, sorry.