OK, talk about synchronicity, yesterday I plugged the Ety 4s into my Meir cantate right after listening to my K701 because my kid had the tv loud and I wanted isolation.
I was reading this thread as I was listening to the K701 and just switched to the 4s to re affirm my impresions from yesterday.
My 701's just have 400hrs so are broken in.
They do have more bass, airiness, and headstage than the Etys but are , for me , from the same sonic lineage.
If you like the etys I think you will like the K701 a lot. It makes sonic sense, to my ears, to go from the Etys to the K701.
I love my Etys but a full size can brings a more speaker like presentation that is different in a good way.
I travel with my etys, on the plane, Yuin PK1 in the hotel and K701 at home unless I need isolation at home.
I suspect you would be very happy with the K701 if you like the Etys.
Remember that that the K701 needs a lot of break in . Out of the box they sound horrible! But even after 10 hrs the difference is significant and at 400hrs they sing a very seductive song.