Unfortunately, these op-amps tend to be of a poor quality and a sound degradation becomes inevitable. The effect on sound quality is an aggressive midrange in powerful passages. In complex music sections the instruments merge together causing the sound clarity to become unclear. Further more, poor quality op-amps can sometimes be responsible for a cold and edgy sound. Detail becomes optimal at both low and high levels.
CD player sounds less aggressive and gains a warmer, more natural sound.
After our analysis of data sheets and listening tests of different op-amps, we have found which parameters are important for sound quality. Other parameters, such as input noise and unity gain stability, are also of importance, if a more practical use of the device is required. We found two op-amps with very promising sound qualities. These being LM6172 from National Semiconductor, and the AD825, from Analog Devices. The LM6172 is the less expensive, with a direct drop-in capability.