A stupid question for which there's no sensible answer.

Getting setup of whatever you have right overall based on room acoustics is always the first order.  Only then can you properly  decide what upgrades to attempt or if even needed.

Getting setup of whatever you have right overall based on room acoustics is always the first order. Only then can you properly decide what upgrades to attempt or if even needed.

This is my point also but most people forget the 2 others embeddings controls of an audio system:

Vibrations and resonance controls,
Electrical grid of the  house and room controls,

These 2 together act differently on the sound quality perception  but together their negative impact is almost equal to the negative impact of the bad or lack of acoustical settings in a room...

This is why i called all that embeddings controls not only acoustical controls...

But yes acoustic is the most evident and powerful .....But the other 2 almost rival it in destructive power...

I know that by personal experience and experiments...

Room Treatment is number #1. No if's and's or Buts.....

Room Treatment is number #1. No if’s and’s or Buts.....

Everybody think that, myself included, but almost no one speak about number 2 and number 3 and together, i said they are ALMOST as important...

Then there is no "if" but there is a "but".....

The word "almost" is well defined in any dictionary...

I'd like to suggest a more systematic approach to answer your question, because the direct response is, indeed, "it depends."  As someone wrote early in this thread, the answer to your question is not independent of your current audio system (components, sources and room).  First try to answer the question, "what is the weakest link in my audio system?"  The answer to that will probably prioritize your approach.  Improve the weakest link, then repeat the process.  Here is the rough sequence for me: new speakers, bi-wired the speakers, network streamer (with DAC), new integrated (with better DAC), better speakers, room acoustic treatments.  Each step improved the SQ.  Along the way I swapped out all cables and added a power conditioner but I didn't notice a significant improvement in SQ.  So, OP, what do you think is the weakest link in your sound system, and why?