Cause of different sound between dacs


Just reading about the Esoteric K 03.
How does the output differ from the Alpha dac, for example.
What exactly is responsible for any sound difference assuming the balance of the systems identical?
Still confused by digital.
ptss
I am not able to audition the two. Perhaps someone with experience can comment?
I was very surprised at how much better my K03 sounds, compared to my Berkeley Alpha Dac (1st one). It has much more detail, more resolution, deeper/wider soundstage - I can go on and on - it was just 'better' in every plane. I am thinking power supplys, dacs and analogue output stage are all superior.
The power supply and analog circuit have the biggest impact on the sound.