Do I need a headphone or speaker to appreciate high-end DACs?

… to appreciate TOTL DACs you need a very resolving transducer.

Not just speakers, the entire audio chain matters in the final sonic result including resolving electronics with lower noise floors, quality of power, power filtration, room treatments, quality cabling, lower ambient noise, etc.  

My headphones are uber revealing, maybe the best headphones for that. My speakers are also revealing. The headphones will always give more detail. 

BTW - an uber DAC for me is the Schitt Yggi+ OG which replaced a $15k DAC. That DAC with both the phones and speakers is end game.

Any headphone must give a natural timbre first...

Then it must gave not details but musical balance where no parts is perceived out of balance from the whole...

i am afraid of the word "revealing" for speakers as well as for headphones...

I prefer natural ( well balanced ratio between frequencies) and holographic ( 3-D spatial perception).

My K340 is not revealing it translate well any recording in timbre and holography with perfect bass impact...

But we are all different... To each his own for sure...

With headphones you will save a lot of money on room acoustics :)

Right!

But i dislike all headphones and it is a miracle that i stumble on one almost perfect but after 6 months of studying how to optimize it right...

There is no easy road without study and experiments in audio... or pay a fortune and buy a bad one million bucks system in some case...

But who will dare to say that a million bucks system is bad?

With headphones you will save a lot of money on room acoustics :)