My biggest surprise after installing the burson v5i was not the sound improvement (i can hear a bit more of the sound, the treble is reigned back for the better, the bass slams a tad more, better dynamics and a tiny bit more imaging.) The BIGGEST improvement for me was the functionality of the opamp. With stock op amp, it felt like I was locked down on the xd05+ up to basically the 1/2 o clock on low gain. But with the burson, all 3 gain levels are ACTUALLY useable along with more useable volume level (across all 3 gains). Was actually skeptical whether such small things would make much change, but was pleasantly surprised (not just by the sound but mainly by the power regulation of the opamp). This opamp to me, seems to really change the entirety of xd05+. The dac/amp’s primary selling point was its power, and with the stock opamp this was regulated poorly, which basically just hinders this unit and makes it not really operate at its max capability. The burson v5i rectifies Xduoo’s mistake and my initial assessment of this unit of “pretty good” became really fucking good.