Above all, it is reliability. And the... I have had several Topping devices. To see the rest.
And ? what about the reliability of the Topping devices you've had ?
I have a Topping Dx7s, it works fine since 4 years now. Its ergonomics are not very practical, as all the Topping and SMSL share the same type of remote, one could expect and ask for a serious improvment on the new top range models ! this would be much mre useful than a new product release each two weeks !t has some minors bugs, too, for instance the automatice exitinction coupled with my computer on USB is working sometimes, not always,
More annoying though not very serious once we know, it has, from the first use, a very audible "ploc" at extinction,
But all in all, no serious reliaility problem for the moment
The sound is extremely good on the headphone output (unbalanced. (I don't have a balanced connector on my Sennheiser 560S).
The sound is correct on line output, but definitely less excellent than the headphone output, no matter what the measured datas say, line output is quite perfectible..
Of course, I'm talking only about the Dx7 and DX7s series, not the rest of Topping range, I've ever used nor listened to any other Topping device.