The AV100 and AV200 processors found on Asus's Xonar line of sound cards are known to be C-Media's CMI8788. Even Asus's drivers say so:
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Naturally, at least one person would eventually make use of that fact to install Xonar's drivers on other CMI8788-based cards to get software-emulated EAX5 found on Xonar's drivers.
There are at least two methods to install a driver not meant for the device, I'll touch on one that works (in enabling EAX for non-Xonar cards), and one that didn't.
Changing the subsystem ID in the driver .ini/.inf files
It didn't work, so I won't go into details.
The driver installs, but does not work - Xonar Audio Center does not run, digital out works or doesn't depending on whether you had installed the soundcard's original drivers previously, analog out not tested, no DS3D GX.
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Changing the card's subsystem ID in EEPROM
If DS3D GX is enabled through Xonar Audio Center, then that center must be made to work (it has no ini/inf that can be edited). The other method to disguise a card as something else is changing its device and subsystem ID.
Fortunately due to the apparent frequent failure of EEPROM of Xonar series of cards people wrote a EEPROM writer for it:
Xonar EEPROM Failure - AlsaProject
When run the program gives you a list of device IDs with their respective cards' names to write to your card's EEPROM, including Razer Barracuda AC-1.
If your card is PCI, choose a PCI card; if it is PCI-E, choose a PCI-E card.
Asus's naming system - PCI-E versions of the cards have an X at the end of their name - DX, D2X, STX, only exception is HDAV1.3 which is a PCI-E card, with the PCI version being HDAV1.3 Slim
This is where you need to trial-and-error - not all, if any, of the Xonar drivers/IDs work with your card's analog out, digital out worked for me in all cases I tried.
For HT Omega Claro, the one that works is Xonar D1.
After changing EEPROM:
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Testing if DS3D GX/EAX5 is working
First there is the above program to tell you what features the card has.
Secondly you can run games that are known to crash with Xonar's DS3D GX (a lot), if your card now crashes the game, congratulations, you have managed to recreate the DS3D GX crashing games part on your card.
Any other suggestions on testing EAX5 functionality are welcome.