Thank you kindly for your response and insight. It should have occurred to me that the min-DIN on these cards have their own implementation and are not much connected to the activities the rest of the system is undertaking. I sent a small donation as a token of my appreciation. Your dedication to these projects is much appreciated!
Unfortunately, my set lacks RGB inputs, so S-Video is the best I can manage until a better set comes my way. I do have a VGA-to-S-Video/Component transcoder, I was just hoping not to need it.
Luckily, the 480i S-Video output on the card is perfect for my current application, assuming lag isn't an issue. I was hoping that lower resolutions would still be useable via the mini-DIN in the event I wanted to emulate such games that would require them in the future. That being said, I have an HD 7750 and the aforementioned transcoder for better performance and compatibility in Windows 10 should the occasion arise.
It seems that the part I was missing is that there is an official AMD driver for these legacy cards for Windows 10. Earlier today, after reading your post, I rebuilt the system and managed to get everything functioning appropriately.
For those who may be reading in the future, here's an excerpt from the AMD website:
ATI Radeon™ HD 4000/ATI Mobility Radeon™ HD 4000, ATI Radeon™ HD 3000/ATI Mobility Radeon™ HD 3000, and ATI Radeon™ HD 2000/ATI Mobility Radeon™ HD 2000 Series Graphics reached peak performance optimization in October, 2013.
Driver support for these products under Windows® 8.1 and Windows® 10 is only available via Windows Update. Please enable Windows Update to allow it to automatically detect and install display driver version 8.970.100.9001
(From: https://www.amd.com/en/support/kb/relea … win-legacy)
For whatever reason, Windows Update did not find these drivers when I installed the card initially (using the "Generic Display Adapter" drivers instead), but did find the driver when I did a clean install of Windows 10 with the card already installed in the system. Even then, the first attempt failed but was successful after the second attempt.
I tested the card via the DVI-I port with my monitor, and it is performing as expected. While I haven't tested the on-board S-Video output yet, I'm pretty pleased that it seems my issue was never really a problem at all.
EDIT: Just tried the S-Video output on my CRT TV and it's working as intended.