Unfortunately I haven't had any experience with the PAS-16, but I do have three Aztech cards that I can comment on.
1. Sound Galaxy Washington 16 138-MMSN837 AZT2316 chipset
This is using the line-out on the card. My particular card does not have the TDA1517 amp installed on it, it only has the line-out option. All unnecessary inputs were set to 0 (mic, line-in, CD-in)
Very low noise level, no discernible ground hum, white noise or "computer thinking noises" at normal listening levels, even with headphones. Only if the amp is turned up very high you'll be able to hear some low level white noise, this is obviously without playing anything through the card. If you play anything through the card at this level, you'll definitely not hear the white noise.
I'm not sure why DionB's Aztech card is so noisy, must be some issue with it, as all my Aztech cards are very quiet, only my AWE-64 Gold and Turtle Beach Tropez+ are quieter. This is in all my retro PC's from my 386 to Tualatin.
Genuine YMF-262 OPL3 chip. The FM on this card is very clear and crisp, no distortion at all. The only card I've heard with clearer FM is the Turtle Beach Tropez+. I really like the clear FM on this card, however others might not like it as it isn't "grungy" and filtered like it is on the SB Pro and other clone cards.
SB Wave output. Fully SB Pro compatible, haven't come across a game that the SB Pro option doesn't work with it. However, this is the one weak point of the card, There is no low-pass anti-aliasing filter on the SB output, so there is ringing and very slight distortion on the output. Not a deal breaker, but I definitely prefer the output to have an anti-alias filter to clean up the sound. The Crystal CS4232/4235/6/7 chips are the best I've heard when it comes to SB Pro output, the anti-aliasing filters on these chips are just about perfect.
16-bit wave output in Windows 9X is really clear as well, no over-powering bass or highs. The Crystal CS4231A CODEC has a really good S/N ratio, MP3's sound really good through this card.
Has a wavetable connector that is also very good with all the wavetables I've tested on it, no distortion or extra noise introduced as a result. The MPU-401 on it doesn't suffer from the hanging notes bug that plagues most SB16's. The card is also 100% compatible with SoftMPU if you want to attach a Roland MT-32 or similar to it.
The only problem with this card in pure DOS/Windows 9X DOS mode mode is that there are no DOS utilities to change IRQ, DMA volume levels etc. Seems like you can configure it in WIndows 9X only. I found out that the DOS volume control utility in the Turtle Beach Tropez+ software works with the Aztech card, so at least you can change the volume.
This card is very close to the perfect DOS soundcard, the lack of an anti-aliasing filter on the SB output lets it down.
2. Sound Galaxy MM PRO16II 138-MMSN845 AZT2316R chipset
Used the line out on this card, this one does have the TDA1517 amp on it. All unnecessary inputs were set to 0 (mic, line-in, CD-in).
This card is pretty much identical in all aspects and performance to the Washington 16 above but it has better drivers and software, particularly in DOS. It has a utility to set the DMA/IRQ and volume levels in DOS, so it's the better choice if you're in DOS most of the time.
3. Sound Galaxy 16B SRS 3D (sorry, no FCC ID on this card) AZT2320 chipset
Also used the line-out on this card, no TDA1517 amp present. All unnecessary inputs were set to 0 (mic, line-in, CD-in).
It's an OK card, has a genuine OPL3 chip built into the AZT2320. It has the OPL logo on the AZT2320 chip. The FM sounds more like other SB clone cards, a bit grungy and distorted. No anti-aliasing filter on the SB Pro output. It is a very quiet card, no ground hum or white noise at normal levels. 16 bit wave out is also very good. The AZT2320 chip was developed in conjuction with Yamaha, www.thefreelibrary.com/Aztech+announces ... a017449504 so it's probably the predecessor to the YMF-715/8/9 chips.
No hanging notes bug on the MPU-401 and SoftMPU also works fine on this card.
It's a PNP card but can be set up easily on a non PNP motherboard. Has good drivers and software, works fine in DOS and has DOS utilities in the drivers as well.
HP made soundcards using this chipset, they can be found cheaply on EBay, however the HP cards lack a wavetable header.
Jesolo is the resident expert on Aztech cards, he has a bunch of them, so hopefully he'll see this thread and comment on it.