Bal. cables are expensive so people will run less quality. A single at twice the quality in Se is going to make a difference too.
That may be true for people who just kind of stumble upon balanced setups (rare, I assume), but if I didn't have the funds for a proper balanced setup, I'd go for a proper SE setup (at less cost). At least you can't generalize that just because someone is using a balanced setup, they are using lower quality conductors. And low quality balanced cables still have inherent benefits over low quality single ended cables.
From
Wikipedia:
That's the good thing about differential: whatever you add to or subtract from both lines (noise), the difference is still the same (noise rejection). How relevant that is depends on your environment (how much noise there is), the length of the cables and the shielding used, and many critics say it's only relevant in much longer cable runs than you typically encounter at home.
You're also avoiding a shared ground, said to reduce cross talk between channels, leading to better channel separation. Logically that makes sense to me, though I've not knowingly been the victim of diminished enjoyment due to cross talk.
My two channel system is still single ended so far, with a 15ft RCA cable between preamp and amp, running parallel to various other cables, including the power cord of a surge protector. Can't say I noticed noise, but some distortion manifests in other ways than directly perceived noise, like maybe worse imaging or loss of details, or whatever. Impossible to judge without proper A/B. Though it's clear that it's not super bad.
The most important thing is always the transducers.
Plus there must be a reason Dave is Se. They could have easily put Bal. if they desired.
Well, cost and space, presumably. Truly balanced would mean four signals generated (for stereo), and it's expensive enough as it is.
It does have balanced outputs, though - probably via inverters, as I read about the Hugo TT.
Given its acclaim, a single ended Dave is apparently still better than most truly balanced DACs.
But, by your line of reasoning, there must be a reason the Yggdrasil is balanced (truly so, with two DACs per channel).
I have advocated for a single ended Yggy in the past, though, to avoid the cost impact of doubling most everything and the possible sound impact of using summers for the single ended out.