I went on my thrift store adventures 2 days ago (Mar. 24th) and found a box that said Sound Blaster PCI128 (which is what I thought was in there) for $12.99 + tax. Once I looked inside, I saw not one but two ESS AudioDrive ISA Sound Cards with a 56K Modem manual, free 100 hrs for AOL and CompuServe, and a driver's CD for one of the ESS AudioDrive cards.

Specs of the two cards:

First one:

1Acer/SerTek S521 non-PNP
2Jumpers for setting the IRQ/DMA/MIDI*/SB**/Base/CD-ROM***/Joystick
3ESS AudioDrive ES1688f FM Synthesizer
440-pin IDE CD-ROM ATAPI
526-pin WaveTable header
6Unknown header (J4)? <-- can't find any documentation
72x 4-pin CD-ROM Audio connectors (old style and newer style)

* SB-MIDI or MPU-401
** Sound Blaster 2.01 or Sound Blaster Pro 3.01
*** Useful for systems that have the single channel IDE or for broken secondary IDE on the motherboard

Second one:

1AW26 P/N: MBP-000078 <-- I have no idea what the make is.?
2ESS AudioDrive ES1869f
326-pin WaveTable header

For the price I paid, that's not bad at all. What are your thoughts? Picture(s) to follow soon.

Edit: found the first one with more info. It's an Acer brand card, according to the FCC ID.