How much difference between new/refurbished amps and amps that need more than a tuneup?

I have been enjoying my ADS 990 and Conrad Johnson 2500 combo for almost a year. I have been waiting to find the right time to spring my other set of speakers ADS 980 on my wife. It's a tuff situation. The 980's sound deeper and far more detailed compared to my 990's. Oh well (shrugs should and shakes head)
I found an amazing deal a week ago here on Audiogon on a CJ 2550 from member stereo5.
It took a nano second to hear  the clear and huge difference  between amps, the 2550 rocks. my 990's with my CJ 2550 sound deeper and more accurate than the 980's powered with the older CJ 2500. The more I progress in my journey thru HiFi the more I learn how important it is to audition every combo before bonding with it.
Not sure what  the question is, but the MF2550 is less than a year old and should need no maintenance.  The 2500 on the other hand may need cap replacement or something similar.
With time, any amp design will be altered as new or better parts are introduced. And as Stereo 5 points out, your 2550 is much older. Whether it needs new caps or repair, I don't know, but I would bet that the newer amp has upgraded parts that will explain the difference in performance.
Making a statement that my new CJ 2550 I bought from you blows my older 240w CJ 2500 out of the water in every department. I guess if there was a question asked it would be " at what point does one need to replace or have an amp serviced?" 5000 hours at 40% volume?


providing an amp works on an operational basis without any issues, Conrad Johnson claims, that capacitors/other critical parts are good for 20 years.  Good to read that the 2550 found a new home. Hope this helps.

Happy Listening!

New vs old. I have not bought real high-end tube audio gear, but from what I see all the gear new & old uses the wrong components. So, I simply buy vintage and modify/upgrade with best parts & tubes. And, it makes a real difference.