Don't mean to argue with anyone, but I find it odd when I read about people not being able to hear the difference between balanced and single ended. To my ears it's such an obvious difference in the placement of sounds that I can't see how anyone wouldn't be able to immediately tell the difference after listening to single ended for a while and then switching to balanced. It's not even a question of whether your ears are good enough to hear certain frequencies or anything like that. The main difference is in, as I said earlier, how sound is positioned. The main difference I hear when switching to balanced input is greater or "exaggerated" separation, and and overall wider soundstage/headstage. Again, this difference is so jarring to me that I don't understand this talk about not being able to tell the difference.
I'm not saying that this change is necessarily better though. I've heard a few headphones via balanced and single ended connection on a few different balanced amps (Questyle CM400i, Acro L1000, Opus #2 DAP (2.5mm balanced). The headphones were: Ether C (non flow), Ether Flow, HD600, Audioquest Nightowl Carbon, Audeze LCD-i4 (not mine, my cousins), and finally the Hifiman Edition X v2. Out of all of those I can honestly say that I only prefer(d) the sound of balanced over single ended on the Ether C, HD600, and Nightowl carbon. The reason relates to why I used "exaggerated" to describe separation and soundstage/headstage via balanced. On headphones with an already respectable amount of headstage, the increased separation sounds "off". It's almost sounds too wide or too separated and I don't like it. This is why I've come to the conclusion that balanced really only benefits headphones with a more intimate/congested presentation, i.e. closed backs, hd600/650/6xx, etc. After I heard the HD600 balanced, and going back and forth A/Bing, I never went back to single ended.
Again, I'm not trying to argue. I can understand a number of posts about not seeing the benefit of balanced, but I just read a few posts here about not even being able to tell the difference in sound and only seeing the benefits balanced gives in driving power or better components. Sorry if my ears are just really weird and no one is hearing what I'm hearing, but I just wanted to add to this thread in hopes that someone wont cast aside the possibility of trying balanced out.