The difference is: Studio V 3rd Anv has more detail, better transparency, superior instrument separation, also leans brighter in tonality so it sounds clearer, however this isn't without the issue of hiss using low impedance IEM, something that will drive you absolutely batty if it's to much to handle (depends on the pairing), something IHIFI 760 doesn't have at all (no hiss). The HIFI has a warmer smoother tone to the mid range, which shows an emphasis in the lower mids to my ears, also better layered soundstage than Studio V along with a pitch black background. it's weaker in separation and can only start matching the Studio's detail at rather high volumes or from line out (something the Studio doesn't have)
As for pairing with balanced armatures and dynamic IEM, they do both well, it's just the 760 needs a good 50-100 hours to open up and sounds it best imo. At first I didn't like the sound of balanced armatures with 760 they sounded dull and lifeless, however my opinion has changed putting hours on the player, and might I say I am not the firmest believer of DAP burn in the first place. My 760 stays paired with ER4S a lot of the time and very much so right now from line out.
The 760 has a specific timbre or tone to it's mid range that makes Studio V sound dry or sterile, for those who like a slightly warmer smoother sounding DAP 760 may be for you. it certainly pairs better with brighter sounding gear like Grado, ER4S, RE0, MDR-V6, etc etc...If the headphones to warm you may not get enough clarity from 760, unless pumping the amp section. if you can however balance out the tonality between your headphone and 760 it can work well. I'm using mine paired with JDS C421 (OP2227) at the moment. when I plug ER4S into this combination sounds far better than what the Studio can produce from headphone out. So keep in mind that line out there with 760 opens up a world of possibilities and adjusting the tonality / signature with amps.
This sounds absolutely great far better than both 760 and Studio V headphone out. Some of the cleanest, detailed, transparent sound I've heard.