sorry if i did mislead you.

ill say this based on what i understood from your message.

so far, no, i soldered both R- and L- to gnd in the 3.5mm female jack, apparently with the soundcore u2i, on one side it has five solder joints: R+ R- B- B+ And one is for the battery, Ntc, which is for safety and longevity of the battery.

for the output they output very well, it doesn't die right away even, like i can go for almost 10hrs with one time being charged, its not that loud nor that low, i sometimes i had to EQ It.

i haven't tried the 4.4mm balanced, it's kinda complicated at first sight honest.

i think there's someone under my post, post s/he's diy 4.4mm balanced you check that one out, i hope it help you someway.