The time I got to compare inexpensive to expensive converters was done blind, at a mastering studio my friend owns here in L.A., about three months ago. A few of us were there, checking it out together. The difference was clear to all of us, but it wasn’t comparing the two interfaces in question on this thread. It was between an Antelope something or other, an M-Audio of some sort, and a UAD Apollo. The Antelope sounded the most clear, “big” and defined, with the UAD pretty close behind though not quite at the same level of detail. The M-Audio was definitely more muddled in comparison to the other two, noticeably not as clear and defined. The preamps were completely bypassed – this was only D to A straight from his mastering DAW. Again, this was a totally blind test for us, with all units hooked up to the same DAW and my friend switching directly between them (just a short pause as the DAW switched to the different interfaces), all going to the same super high end mastering monitors (I forget the brand). And again, it’s not between the ones that you’ve mentioned here – I’m just saying this as a general point of reference for cheap vs. more expensive in the case of converters. All three of us “voted” exactly the same. Others may not care about the difference, which is totally fine of course!
All of this is to say that a blind test moving quickly between the interfaces is the only way to truly know objectively. Obviously most of us can’t do that!