@fablestruck,
Honestly, subjectively & personally, I lean more towards 1540 sound more than 846...
However, this will also depend whether you just listen to music or other media as well.
1540 has more natural tonality with better emphasis in highs & bass without leaning into either spectrum than 846 which the latter personally I find a little too clinical leaning towards dry & linear...
This is not a bad thing, I am just not a fan of critical reference tuning as sometimes it can become
'boring' after a while or more accurately, some songs, even from different genres start sounding the same.
Also, compared to what is around for IEMs nowadays, overall sound & staging for 846 is very
'safe', similar sound would be the flagship from Audiofly.
But back to 1540, depending what you listen to, especially if it's mixed media, 1540 will give you better overall sound, staging, imaging.
Some might say this is a given as one is a headphone & one is an IEM but personally, I find it depends.
Your source will matter too as will how well recorded your media is.
The only way you're going to know is if you can demo the 1540 yourself.
Hope this makes sense.
Hope you have a great day !