There is a reason why many audio fans and sound equipment collectors prefer vintage models over their highly sophisticated modern counterparts. This article on Stuff.co.nz has some good explanation to it:
Why do so many audio fans seem to prefer a vintage receiver over new receivers with modern technology?
Are there actual reasons that older equipment can sound different or better?
When it comes to receivers and amplifiers, older can be better. The amplifier sections in new receivers often don’t have the power and electrical current capability of vintage models, especially going from a stereo receiver to a surround sound receiver as you did.
The manufacturers saved money by cutting quality in surround receivers’ amplifier sections, then used the savings to add new features such as extra channels for more speakers, Bluetooth, etc.
The power ratings in new gear are often inflated, as well.
In real-world use, an older amp may actually deliver more power to the speakers, despite newer models having higher advertised power rating.
In addition, many receivers digitally process everything, including the volume control. Some feel that this digital processing degrades the sound.
There is also the possibility that older amps’ power is not as “clean” as the newer models and has more distortion, but the mild distortion lends a pleasant quality to the music.
That is the reason lots of people prefer tube amplifiers or vintage speakers. Though the old equipment may not reproduce the music as accurately as modern gear, the listener may simply prefer the sound from the vintage equipment.
In general, though, if you choose carefully you can get better sound with modern equipment than with vintage.
You just have to be careful about what you buy and how you match components together. There is good stuff and bad stuff littering every price point.
You can get much more speaker for your dollar than you could years ago.
Most modern turntables will sound better too, but much of that is by virtue of their newness. Old turntables can have worn platter and tonearm bearings, which seriously degrade the sound.
However, it is in the realm of amplifiers and receivers that quality has taken the biggest hit.
For stereo, if your budget is under $750 a vintage amplifier or receiver could very well be the best choice if you have access to a clean example that works perfectly. The problem for the average consumer is knowing what brands are best and what to look for so you get a reliable unit.
The “golden age” for vintage audio was probably the 1980s and some great, affordable audiophile brands are Adcom, B&K, Harman/Kardon, NAD and Rotel.