Looks very similar to Acer/Aopen S23A

Indeed it does, maybe the eeprom contents dictates what it is.

Will put full images to compare :

NUSOUND:

S23A:

There still are a few diferences.

Both look like generic Crystal cards to me, very common in the budget market in the Mid-to-Late 1990's, often found in machines made by companies like Tiny.

Are there any other 18bit dac soundcards?

Yeah, the CS4236 out of my Tiny branded Pentium has one according to the enclosed manual. It's Pine branded... Pine sold PCChips motherboards with different labels stuck on... Apparently, they are behind XFX (Which would explain why I have an MSI instead).

Can't say I've noticed any difference, given the sources are 8- or 16-Bit and the Crystal IC can only output 16-Bit digital signals as per the datasheet.

Don't know which chip your card has. They usually had good SBPro compatibility though, even demos fell for it, it's a very good clone to be honest, the TSR isn't too heavy either.

this one has a cs4331 DAC wich is 18bit with 94db SNR and it has a cs9233 GM/GS DSP that outputs to the cs4331. It has a 16bit adress decoding.

http://www.alldatasheet.com/datasheet-pdf/pdf … RUS/CS4331.html

So it's an 18bit audio card I think.