After seeing the comparison video and posting that the 4.4mm was potentially technically better I did an A/B listening test myself comparing the Gryphons 3.5mm and 4.4mm outputs.
I used M11 plus into Gryphon via a short Moon Audio coaxial cable and used Shanling ME700 IEM figuring that being easy to drive the power difference between the outputs wouldn’t be a factor. I used a ddhifi 3.5mm male to 4.4mm female adapter so swapping was as quick as unplugging and plugging in. I volume matched just by ear but also tried the test with the volume intentionally higher and lower to see if that changed any perceived difference, it didn’t.
I listened several Diana Krall songs with for the most part only upright bass, piano and vocals so each part of the music already quite distinct - streamed in 24/96 from Apple Music.
I wouldn’t pretend to have the most highly refined hearing and of course there could be some placebo effect since I was listening for differences but my listening impression was pretty much as was pointed out above.
I am sure that the instrument separation was better out of the 4.4mm, there was a slightly better sense of a 3D soundstage, the vocals were further forward in the soundstage and the vocals seemed to come from a more defined location in the soundstage whereas out of the 3.5mm the vocals were from a bigger area in the soundstage.
With full size headphones, especially those not so easy to drive, the increase in power available may also factor in with better driver control.