Most improved last 10yrs: Speaker, amp, or pre?

I would say that entire systems seem to sound better than those ten years ago. The reason for this is probably the effort and expense invested in assembling them. We are all aware of the insane prices for some components, that people are willing to shell out. I don't recall quite as many years ago.
The quality of sound is frequently preferable when using a currently made top notch system, but not always, it invariably is a matter of taste.
I keep systems from several eras. I always think of my main rig first for the best sound and it is the most modern. This is not to say that ten or more year old equipment can't compete. A well thought out and executed system with synergy can certainly be assembled from the good stuff from ten years ago.

I can't say what the biggest improvements have been in the last 10yrs.But I can say reliability is not one of them.

My nickels worth…..

If greater choices means anything it could be that amps have now been the more improved. Namely by a wider selection of hybrid amps.

Preamps however make a strong argument for settling into first place too as it’s taking less dollars to get astride the threshold of diminishing returns with the most recent versions. I’ve seen articles which allude to the facts that even some of the mid to upper tier receivers preamps come quite close to the performance levels of preamps ranging near the $2K - $4.5K arena.

But I’ll vote for speakers. In spite of the fact I’m finding specific very nice to great personal choices get well into the average of $10K, there’s so many out there now which do a more than satisfying job for far less.

Somehow I feel each category here is ahead of the game vs. their constituents of a decade ago… amps in graeter or more broad spread appeal due to design innovations. Preamps seem the one’s favoring value as it’s chief concern. Leaving speakers determined as being improved by technology and materials, best.

I think the Vandersteen 7s represent a quantum leap - they really stood out from all the other speakers I've heard. if the innovations it uses 'trickle down' to where it doesn't cost 45K to get that sound, that will be a wonderful thing indeed...

and I probably would have said 'speakers' even before hearing the 7s.

(it should also be mentioned that some recent production tubes are finally equal to older production ones)

False dichotomy; the tide of increasing technological benefits lifts all boats.

One of the most significant technological changes is the new breed of component, the "new integrated", which incorporates a device for streaming audio, or a preamp, or a DAC or cdp in various combinations. These are allowing systems in less traditional forms and consequently some improvments in streamlining rigs. Utilization of more direct approaches from source to speaker can result in stunning improvements in sound.

Among the most amazing systems I have assembled is one which uses two such devices, neither one traditional in operation, but which together have fabulous synergy. When put together such components are sensational and clearly mark a departure from the old school dedicated source, pre, amp, speaker methodology. I will update pics to show in due time.