Hmm, from what I saw from googling the price difference of those two chips it is only about $20-$25 bucks, so that does not seem to add up (no pun intended).Because there are already multiple products with the same performance that have been out for almost a year now for the same price soncoz sgd1 smsl m500 v2. The d90 and m400 cost a lot more because they use the ak4499 instead of the es9038pro. Also the su8 was known for being a very cheap balanced dac so people assumed the successor would also be a more budget product.