Maybe it was a misunderstanding, I meant the product you linked is not well known to Head-Fi users - certainly i could not find much about it on head-fi. I can see it has a better following on diyaudio.
I will explain-
I have read the datasheet for TDA1387 and I was curious if it was so good, why it is not more well known, even if it's all old stock. There are few sellers for TDA1387 by itself, one seller is offering 20pcs for under $2 with free shipping!
I have to wonder if they are fake, and if not, if they are leftovers that did not pass QC long ago? And if they are fake, could they be delta sigma TSOP-8 DAC in disguise?
I just find it hard to believe if it's actually non- delta sigma, that the chips would be available for so little money.
I couldn't find out anything about Continuous Calibration besides links to a few other old Philips data sheets. Maybe it was their term for R2R? i don't know.
I also couldn't understand why I saw some TDA1387 DACs on Aliexpress with 4x TDA1387 and some with 8x. Though, it seems that one can use a single TDA1387 or run many of them in parallel.
For what its' worth, this is the cheapest price i can find - $36.99 free shipping
https://www.ebay.com/itm/L1387USB-8...HiFi-Headphone-Amplifier-DTS-AC3/323438251474
I believe you at your word and have been finding nice low prices like $30 with shipping for the TDA1387 DAC you linked. I don't think you are trying to raise my interest in a bad product. I can't understand why such a good DAC chip would be available for so little money, and from so few vendors, unless the chip is still unknown to Hi-Fi non-DIY community.