I replaced my E50 not with a D90 but with a, comparable, D70pro Sabre (which I find looks better than the D90

, because I switched from integrated to power amp and needed a preamp-DAC with a rotary knob and more in/out capability. My First DAC, a Toping E30 I switched very quickly for an E50, after hearing them side-by-side. I do not have golden ears whatsoever, but the E30 (first gen) sounded 'really' (audible for me, that is) harsh in comparison to the E50. If it weren't for my change in setup, I'd still be happy with my E50. A friend of mine still has his, and brought it over for an evening. Switching between them there is a difference, but transparent is transparent. I am sure there are people that can consistently tell the difference between them, but after less than a few minutes of listening that difference becomes the new normal. Also, I don't live in a mastering studio