johny_2000
Addicted to Fun and Learning
E1DA (aka Ivan) mentioned this possibility on the description page of his portable DAC #9039S:The rising THD+N must be due to rapidly rising THD (i.e., not due to the N part). I suspect there must be some design flaw in its power supply circuit.
Simplified DAC tests let manufacturers "optimize" the product cost dramatically. If nobody cares about the real load testing why they'll add a heavy steady power supply in a portable DAC? Just 10uF ceramic SMD is Ok for that i.e. hundreds of times cheaper than 4500uF in 9039S. No reason for tens of PCB polishing iterations as well.