Review on Topping ES9038Q2M OPA2134 Amplifier Decoder by Ben Robinson

Like almost all "USB DACs" this one shows ground loop noise from your computer. If you stop the song and turn the volume all the way up, you'll hear a hiss, like a high-frequency, randomly changing noise. Again, normal listening to the speaker is fine. I only mention this as information for those who need a completely silent system. it's not like this. Haven't tried changing this yet, but I suspect if I can find a serial SPDIF connection between USB-RX and DAC I could put in a pulse transformer and isolate them. I've tried using cheap USB isolators but they refuse to run faster than USB 1.1 and this DAC NEEDS full USB 2.0 support. Heck, I also bought a Topping d30 which has 2 SPDIF inputs to choose from. from along with usb. The USB input is loud due to noise floor on the d30 as is this DAC BUT if you use Toslink fiber it breaks the ground and you are noise free. Many motherboards (usually not laptops) have an optical SPDIF output, so the noise can be bypassed this way. I also tried coaxing spdif from my USB/SPDIF dongle to the d30 dac's coax input. still loud! because almost all USB/SPDIF dongles don't isolate the ground. Then I inserted a homemade impulse traffic between source and DAC and the noise was gone! Just like Toslink Optolink, no ground leakage and no noise. It's a lot cheaper to buy a pulse transformer and stick it between the SPDIF coax lines than trying to isolate the USB! for those who need to know, here you are. The USB inputs on both this and the d30 dac are loud, but if you choose SPDIF and isolation you'll be noise free.