Vintage Amps - Pleasantly surprised

A while back, i was given a non-functional Sansui AU-666, which I recently had restored for sh*ts and giggles. Hooked it up to Rega Aras in my bedroom, using a computer source with a basic NuForce uDac.

Honestly, i was not expecting much out of this combo. However, I am blown away by the sound quality i'm getting out of this extremely modest setup. It shockingly possesses much of the desirable 'audiophile traits' one would typically hope for. I'm not saying it's perfect, but for a 40 year old piece, i'm utterly stunned.

And considering the entire setup cost less than 450 bucks, including stands (excluding computer, but which i had already), i could not have asked for more.

Anyone else with this kind of experience using vintage gear?
The technological advancement of amplifiers has reached a plateau in the 70's or 80's IMO(probably much earlier than that), and there is very little "evolution" or "technological breakthrough" in the current new amps introduced in the market.
I had a Sansui AU-7900 integrated that I should never have sold. The somewhat later Yamaha M/MX series amps and companion C/CX preamps from the 80's are respectable also. Be aware, components from that era will benefit greatly from re-capping, a recommended update should you plan to use them frequently.