I previously ordered a same burson V5i-D opamp from maybe a different seller. That opamp sounds similar but almost sounds boosted and sounds more treble airy and lifelike in my opinion.. I dont know how to describe it but almost noisy sounding which brought treble to life. But this one I just received sounds super clean smooth and almost dull and empty? not lively and not engaging listening like the other. Almost like ones "too perfect and clean its dull" and the others "lively and entertaining" Which one is maybe faulty or whats wrong or whats going on i've no idea. it may be because I tried to insert two at once into my xduoo xd05 plus maybe one broke or shorted somehow that'd be my fault. But it sounds similar so they may both be geniune but ones different a little in a disappointing but not bad way.