What's improved the most?

A simple question that has often been the subject of debate: if we were to take the various components that contribute to music reproduction, the actual recording, then the turntable/CD player, cartridge, cabling, amplifier, and finally the speakers, then which of these components have improved the most over, say, the last forty years?
Or, another way of putting it: suppose we could assemble a 'super-system' from each of the last four decades, what would the difference be?
To be frivolous, I would say things are potentially more expensive than ever before, but if we eliminate the systems for the uber-rich, what would the results be?
I think it might be the CDP. DACs have improved to the point where when properly implemented, they can sound as good as most any streaming device. I've only heard the MSB CDP and it bettered any streaming audio at the last audio show I went to.

I don't feel that one needs to spend a fortune as the Marantz SA-11S3 seems to favorably impress some reviewers enough to just keep spinning discs. $4K is not chump change but when you factor in all the costs and complexity of streaming, it makes sense to wait it out and see prices come down on the really good CDPs out there.

To further add to the debate is an interesting review of the Auralic Vega DAC/Preamp by John Darko. He felt the opposite of what a lot of reviewers feel about it: namely that it's DSD streaming function is not that much better than properly streamed redbook CD content, Femto clock and all. It could be his taste in music, his hearing acuity, or just that he's simply not that impressed and not afraid to say so (a trait not common enough with reviewers).

With the constant evolving of streaming audio it doesn't make sense to me to dive in with obsolescence just around the corner. SACD inventory is still large enough and redbook remasters are still being done. With the Marantz SA-11S3 one can also stream audio through it so the best of both worlds can be addressed.

I have yet to hear the Marantz but dream of owning one or something like it down the road. I would also be content to stream from a laptop to it until standardization comes.

All the best,
Your question doesn't change for the uber- rich vs. the peasants. It's always relative. Imo, it would be speakers just because they are after all the weakest link.
Speakers get my vote, driver materials and internal bracing and overall cabinet design are the largest gains in audio. The actual music delivery is greater than anything linked in production chain given the addition of digital media from the cd to wireless streaming and servers, the latter not even imagined by most just a couple decades ago.
Obvously all have improved greatly and the best stuff from 40 years ago would still sound good if properly maintained. That said, I agree with Csontos, its probably speakers but you'd be surprised to learn that things like the plamsa tweeter were already developed.
I think it all has, digital of course has come the longest way because streaming options didn't exist 40 years ago. I didn't even have a PC until 20 years ago. Removing digital, I would say quality and availability have improved the most.

Quality has improved dramatically, across all gear, in all price segments despite the fact that manufacturing methods have become more complex with more options for the engineer/designer. When I was young, it was not a no-brainer that your amp or your turntable would work very long, no matter how much you paid for it. Even good manufacturers couldn't rely on the quality control of the components they used. The iffy nature of it made me more attached to established stores/firms that backed their gear. It was likely that my gear would need service and schlepping or shipping it around was not the easy FedEx affair it is today. Few manufacturers warranted anything. Your town may or may not have had an electronic repair guy who was sober. I once dropped off an amp to be repaired and when I got it back, 6 weeks and numerous phone calls later, not only was it still not working right, it also smelled funny. When I cracked the case I found a cigarette butt in it. Back then, used gear was a real gamble. Part quality and quality control has improved enormously since the 70s.

The other dramatic improvement I've experienced is availability. A greater variety of gear and music and community is accessible to me now than ever before and it is near instant. I can download albums in minutes that I could never even find 20 years ago. Even with vinyl, the change is crazy. I can find an album I could never find when I was young and it's here in days, or overnight if I want! This is just fantastic.

And community! In the towns I grew up in, I was ALONE in loving audio gear. I had NO ONE to talk to who cared about it. As a little kid and even as a young adult, I was limited in range, so I got pretty lonely in this hobby. Now you can commune online. This is the dawn of a great age. I do not take this for granted.
I would have to say LOUDSPEAKERS.
Look at old designs.. hit or miss, basic wood boxes..
Then the Small Thiel parameters came along. then computer work..
So all in all I would give the nod to speakers.
Yes there are great designs from early years.. but those were just luck. Now, even inexpensive speakers can sound really good. Because of all the work that went before.

Though all electronics have also gotten better.. no question. (except maybe some old tube designs.. with updated parts they can still be great.
First of all, forgive me Elizabeth. Computer-aided design is just that, an aid. Ts parameters have been probably the most important factor in speaker design for a very long time. So they've been getting it right for just about as long, the main limiting factor being speaker driver design and the limitations of the materials themselves. Probably what you meant to say. The level of hit and miss you alluded to is relatively constant in comparison.
There were always good speakers, just not so many of them.
There were NO good IC's and speaker cables.
Right now, this very day, a pr of KLH 17's with the Dynaco tube stuff available then, hooked up with oh, Analysis Plus Copper oval wire, would make music on a very high level
and satisfy any rational person, if not a audiopile.
Preamps have made the biggest improvement for me .
Magnat Superflow speaker cable will never be beat, made in the seventies. Same goes for silver Litz ICs.
In my opinion, the greatest improvements have been the design and quality of specific components such as resistors, capacitors, inductors, transistors (especially transistors), cabling, speaker driver technology and speaker cabinetry design along with better electrostatic design. I think the amps and pre-amps back in the day were actually very good. But, replace the poorer quality resistors, capacitors, coils transistors and possibly tubes and the amps and pre-amps would do very well today. The speaker driver technology and actual speaker design is much better today. The recording technology and methods in the 50's and 60's for especially classic Jazz is night and day better than today, in my opinion. except for a few specific recording companies. The transistors of old really couldn't handle the power requirements, frequency ranges and bandwith requirements that the much more linear transistors of today can handle. I can't tell you how many older amps I have upgraded with much newer more linear pre-driver and driver transistors, rebiased them and put better heatsinking on them and wow!
I think the advent of really good power conditioners has made a big difference.
Wires of all types!

- Copper is now at very pure levels
- Silver conductors are an option - gold alloy for the rich
- Shielding has improved - up to three shields on some interconnects
- cable design using difference conductor diameters & shapes
- cable geometries improve performance
- insulation now prevents corosion of conductors

Let's not forget the high quality items like
- silver/gold alloy solders
- connectors - RCA/IEC/Mains/Spades
- outlets

All contribute to the better performance of our beloved components
The cd player!