What's improved the most?

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,
Nonoise

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.

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 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.