I'm using RCA and Dynaudio Focus 110a, D70 connected to Raspberry pi 3 via USB. My hdd with music died day before Topping arrived, so I only left just with several albums (Slayer, Rebecca Pigeon and AC/DC), so no serious subjective listening tests yet performed. It's a level up for sure - even without burning in D70 sounds better than D50. Not even a sign of harshness, great instruments separation, better focus and soundstage, guitar sounds way more natural. Overall d70 sounds less "digital" than d50. Recently I tested Gustard x26, fantastic dac, a was shocked with SQ. Topping d70 didn't produce same wow effect, but it cost three times less and I'm totally satisfied for now with it.
Build quality superb also, even better than Gustard, solid and nice looking unit. Can't wait to try i2s and aes inputs.