How to improve the sound from FUBAR II USB DAC

Fubar II USB DAC has been wanted by me to pair with my macbook. Thanks to Mr Hanhan. I buy this from him with very good price.
The function from Fubar II this was simple, it will take the digital signal from laptop USB to not pass the part amp of laptop. Output from fubar this will be lured to input from little dot amp. The package of the sale was inside gotten the cable rca, the cable usb and the adaptor as power supply.The short specification from Fubar II this used Burr Brown PCM027, OPA2604 and JRC072 as buffer. First impression time the first time in the test, the separation was better, staging more better and increased the weight of the sound.Mark II this was gotten by the difference with the standard component after being replaced several of his components. In fubar this that was changed was capacitor and op amp. Dourex was used to replace capacitor. To op amp after being carried out by several rolling amp, among them LM4562, OPA2604, etc., was found that gave the best combination was OPA2111 and AD8066 to replace OPA2604 and JRC072, with AD8066 was placed in the position buffer replaced JRC072. The first testing really gave results that were not expected. The SQ rise very drastic compared to the standard. The voice was seen very neat, there was no impression hurried, the lip explosion and the voice breathed canned be heard in more detail.For the price upgraded that was not too expensive could be said by SQ from fubar II drastic increased . Possibly this the solution for that wanted to look for USB DAC with the budget that was not too big. I hope my short review can helped.