A set of remastered sounds for AOPID: http://simplici7y.com/items/aleph-one-pathways-into-darkness
These are 6 dB quieter than the originals (an attached text file explains why), but also significantly less noisy, much crisper due to the addition of higher frequencies that were absent from the originals, and in some cases free of substantial audio flaws like 60 Hz hum on a lot of the Headless sounds or digital clipping distortion on some of the explosion and weapon sounds.
Note that most of these are not exact reconstructions of the missing audio data, but best guesses that I put together in iZotope RX5 Advanced; in a few cases, however, I was able to use the CD-quality audio sources. Also, make sure you have 16-bit audio on, or you’ll get the original sounds. I also suggest pairing these with W’rkncacnter’s HD AOPID graphics for best results: http://simplici7y.com/items/hd-aopid-graphics