Late to the thread but it’s not placebo. I have the D10s. Some models have the 1656 in the circuit, while other have the opa 2134. Adding another opa1656 to the board via the interchangeable option does indeed change things. I like the stock sound of the D10s to be honest, nice dark background with the stock LME49720 and its clean enough but and it is a pretty big butt…I mean but the stock op amp by comparison to the opa1656 is a little ‘boxy’. What’s inside the box is good, clean music but that’s all, there’s not much width to the soundstage or depth for that matter but again it’s still very good and credit to Topping a very good value dac.
The opa 1656 switches things up! The soundstage widens by a mile, gains more depth, drums have more weight as do bass lines, vocals come forward a fair bit more and sound more live, a lot more live. Treble is more accurate and pinpointing sounds is easier. It’s quite a bit of difference but I can see why people would settle for either choice here too.
I have a Burson V51-D on the way which is reputed to be another big step up from the stock chip so looking forwards to that.