One remark, please: After having read tons of reviews, I had understood that there are basically no differences between DACs of different manufaturers. If I got it right, DACs are technically fully developed items. And a DAC chip only costs some cents - so there is no need for manufacturers to use or even develop cheaper DACs.
A completely different point is the quality of the amp and the disturbance of the signal. So, using an external DAC and external amp on laptops will probably improve the sound. Not because the DAC chips are better but because of disadvantages of the compressed construction of laptops.
Just my 2 cents