I'm going to go against my better judgement a bit here, but maybe I can contribute in a way that will help someone.
For the EEs out there, can you please explain why the D50s does not need balanced line outputs? I refer to this write-up by Benchmark:
https://benchmarkmedia.com/blogs/application_notes/balanced-vs-unbalanced-analog-interfaces
Lets take a look at some of the information presented here.
Consumer-grade balanced interfaces can only provide 3 to 6 dB SNR advantage due to the relatively low +14 dBu (4 Vrms) signal levels.
The so described "consumer grade balanced interfaces", at 4.0 Vrms, form the vast majority of the XLR balanced connections seen on the types of audio devices tested on this site (as opposed to the +24 dBu 12.28 Vrms "professional" balanced interface level). These numbers are based on laboratory best-case testing scenarios, and the SNRs of the equipment used as examples in the writing of the article are in the -127dB to -135dB range.
If we give maximum assumed benefit to XLR and say that using an unbalanced RCA connection carries a 6dB SNR penalty, the noise floor of most of the best measuring DACs on this site will still be well below audible levels with the unbalanced connection.
"But what about this!?", you say!
In addition, balanced interfaces provide rejection of many types of interference. This immunity to interference can provide a 50 to 100 dB reduction in these unwanted noises.
Well, in this case they are referencing the potential rejection of ground-loop interference, which later on in the article they state more specifically.
50 to 100 dB rejection of ground-loop interference.
Elimination of ground loops is a true and widely recognized advantage of XLR connections. If you're having issues with ground loops and your equipment already has XLR connections, you might as well try them. If your equipment doesn't have XLR connectors already though, there are other solutions to ground loops that will prove satisfactory.
I think it's important to determine context and requirements.
If the question is "Does a +24dBu 12 Vrms signal level XLR balanced connection have a scientifically demonstrable noise advantage over +8.2dBu 2.0 Vrms unbalanced connection?", then the answer is unequivocally yes. This is true and I'd never argue that it isn't.
If the question is "Would commonly seen 4.0 Vrms XLR connections offer a meaningful improvement in noise level over 2.0 Vrms unbalanced connections on a DAC with a ~-130dB noise floor?", well, you can debate endlessly on what constitutes a meaningful improvement, but my take on that is there is really no benefit.
Given the performance that $100 devices have proven capable of in the current market, if I were looking to purchase a "premium" grade DAC in the $400+ range, then I think it's entirely reasonable to expect balanced XLR connections on the device. The added cost and bulk of the device are already a given, and they really will help you to minmax your signal path. That said, on a $100-$250 device like the D50s, I think there is really no need or place for balanced connections. I'll be using mine with Koss ESP-95X, which doesn't have XLR inputs anyway. I think many others are pairing this with the Atom or similar, same applies.
If balanced XLR connectors are a requirement for you in a DAC, say if you already have an extremely performant amp with balanced inputs, there are lots of great options, such as the Topping D70.
The other place these connectors have a clear advantage is in professional audio settings, where you're most likely to find them. These types of noise effects are cumulative, so when you have a large number of devices in your signal path (think 4, 8, maybe more!) in an electrically noisy environment, the advantages start to become more applicable.
Of course, when the third sentence of the cited article is "In all cases, the balanced interfaces will provide better performance."
, it's easy to stop reading and form the conclusion that XLR connectors should be mandatory! Especially if you came into the article with a pre-existing preference for balanced connections and you were really looking for validation more than information