@ConteZero : maybe, I am not getting entirely what you're saying, but I think you're mistaking Envy24 (with chip marking "1712") and later Envy chips (like Envy24HT-S for which is the initial question). they technically are from the same Envy-family, but later ones are marked as VT172x (for example Envy24HT-S is VT1721, VT-prefix, because VIA acquired the IC Ensemble, which made the original Envy chip) . So, what @holdencars11 wrote few posts above is mostly correct - Envy24 (1712) chip itself has full DOS support (but no any DOS software), it even has OPL3 emulation in hardware, which we've never heard (by "we" here I mean the retro community) how good or bad it sounds due to lack of software. On the other hand VT172x chips are with DOS supports fully removed. Also, Envy24 (1712) DOS support works only when AC97 codec is installed on the card (you can see the Block Diagram in 1712 datasheet to understand why) and only couple of such cards with AC97 codec were made, because most of them were pro-grade cards not using such cheap technology as AC97 codec. I know only two Envy24 (1712) cards that have AC97 codec on board: "Terratec EWS88" and "Hoontech DSP Media 7.1" - in fact both are high-end and you can say even pro-grade and that's why they have both AC97 codec and high-end DAC chips, but having AC97 codec makes them that in theory (if software is wrote) you can make them work in DOS. Last, but not least Envy24 (1712) supports DDMA, which actually makes writing DOS software to initialize them to work in DOS easier, because then such software is reduced to 2 steps: init the DDMA and init the AC97 codec on the card. Anyway, I have "Terratec EWS88" and for years it is on my TODO list to make it work in DOS, but too many projects, too little time.