Audiophiles have been rolling (replacing) op-amps in their DAC units for years. In the computer audio world, high end sound card units from Creative and Asus have had replaceable op-amps in years past and their owners swear by the increased audio fidelity from changing them out. Audio Science Review has taken the challenge to roll the op-amps in a Topping D10 DAC as the op-amps in the unit are socketed. Then afterwards the unit was tested using a $28,000 APx555 Audio Analyzer. The op-amps that were tried in the unit included the OPA-2134 (shipped in the Topping D10), Muse 8820, Muse 8920, LME49720, OPA-1612a, and a 994Enh-Ticha Dual Matched Discrete Operational Amplifier. These ranged in price from $4.79 for the ones that shipped with the Topping unit to $94 each. Here are the results presented in chart form. This chart is hugely amplified (vertical axis) relative to what I normally show. Despite that, the differences are tiny. Assuming you want to go by that difference anyway, the best performance was achieved using the op-amp shipped with the unit, the TI OPA2134!!! In other words, the designer knows best. I also looked at SINAD differences (not shown) and there was no difference to speak of there. The unit itself varied in performance by 1 dB there and that was what I observed as I changed op-amps.