May consider this over the topping a90.
As good as the A90 is, I Have bad luck with the second unit of it, having some high pitched noise coming from inside (some coil or the power supply) which got even louder the more time passed.
If the power supply is as good as smsl says, I might consider.
No badmouthing the A90, it is unit-dependant and I just got bad luck.
Though there are clearly ways to prevent this (more quality coils for example).
Have to ask shenzhenaudio for a refund and hope they're customer friendly