When it comes to budget desktop DACs in the $100/- range, the choice usually boils down to either the Topping E30, the SMSL Sanskrit 10th MkII, or the (slightly cheaper) Schiit Modi 3+ DAC.
I originally got the Topping E30 for a very specific requirement, i.e. to use as an external DAC for a decade-old Yamaha CDC-697 CD player, which is paired with an equally old Yamaha R-S300 stereo receiver. Yamaha tends to use Burr-Brown DACs in their equipment, which tend to be very warm, smooth and lush. When paired with the R-S300 stereo receiver, which also is a warm-sounding amplifier, it eventually became a case of too much of the same thing.
That is when I decided to try out a more current, external DAC; and having heard good things about the AK4493 chip's implementation in the Topping E30, went ahead and bought it. However, it turned out that the newer models of the E30 had replaced the SPDIF receiver from an AK4118 receiver chip to a Cirrus Logic CS8416 chip, which was known to have clock synchronization issues with SPDIF outputs from most old CD players, resulting in frequent skipping/missing of sound.
No such problems had been reported by anyone with the SPDIF receiver chip inside the SK10 MkII, and so, I replaced the E30 with that. It works fine as an external DAC with my old CD player, although reviews on Audio Science Review have reported that jitter is significantly higher on the SPDIF input when compared to the USB input. However, for 16-bit/44.1KHz CD music listening thru a stereo amplifier, I am not finding any audible issues.
Detail retrieval in the highs and mids seems to be better than the old, built-in Burr-Brown DAC of my CD player, while bass seems to have tightened up and become more taut. It is definitely more musical & warm than the drier, more analytical sound of the Sabre ESS90382M chip used in the FiiO BTA30 Pro Bluetooth DAC; and to me sounds a tad more musical than the Topping E30s implementation of the same AKM chip too.
I don't use it as a USB-DAC, but there are enough expert reviews out there to vouch for it's performance on USB - being as good (if not better) as the E30 or Schiit's Modi 3+ - so one can't go wrong with it in this price category.