@SoulsHarbor These comparisons/opinions (whether positive or negative), including the OP's post with regards to audibility are effectively
useless in reality because none of these comparisons are volume-matched. People are effectively just "swapping" one component out for the other in their chain and then subjectively assessing what is coming out of their speakers/headphones. This is a completely improper way to test gear since depending on factors like output voltage, impedances, amplifier gain etc. the volume of the sound coming out of your speakers will vary. People may try to volume match "by ear" or in rare cases with a sound level meter but none of these are accurate enough to match, and we know from a scientific understanding of human hearing that volume 1-3 dB (or less) can affect the tonal balance of music and how it is interpreted. Louder music almost always sounds better.
The "proper" way to volume match is with devices like a good quality true RMS multimeter, scope, or maybe a calibrated microphone which virtually no one does in these comparisons. And those who understand the science will generally not waste time doing this because they will understand the result will be imperceptible, unless maybe they suspect a component might be misbeaving or performing differently for a specific reason. Better yet, we literally have objective data showing the frequency response of both devices are demonstrably ruler flat and distortion is inaudibly low, so unless there is a problem with one of your other devices in your chain then there should be no difference if the Benchmark and Topping are volume matched- they sound the same. The only reason to buy the Benchmark over the Topping is perhaps maybe you want a professional American-made product with good warranty, maybe you want something larger with a nicer chassis, maybe you want something rackmountacle, maybe you want to match it to other Benchmark gear, maybe you just like the looks of it, maybe you have too much money burning a hole in your pocket. Buy the Topping if you want state of the art performance for a fraction of the price in a compact formfactor (there are other Topping units that perform just as good for even cheaper as well).
What subjective reviews are perhaps good for is comparing the build quality, faults, or usability/user experience of the product, which might be important to a buyer. In your case with Qudelix, it also is measured to sound virtually identical in SE and balanced confirmed by multiple measurements, the major difference is that balanced mode has 4 times the power available allowing you more headroom and higher peak listening volumes, and the ability to get more volume out of harder to drive headphones. So I'm almost certain of your observation of "balanced being clearly better" with the Qudelix is down to higher output volume and nothing else. Meaning if you were using a headphone that is easily powered in SE, playing it at the same volume in balanced will sound identical if you were to match the volumes.
I'd encourage you to watch the ASR youtube channel where Amir talks about a lot of these concepts on video, might be easier to digest than a lot of conflicting or confusing discussions in text.