1. au30mmed.zip Driver
2. readme.txt File Contents

readme.txt Driver File Contents (au30mmed.zip)

Replace the "au30mmed.inf" file in the Aureal vortex2 ref. drivers
with one from this ZIP before you (re)install and the S/PDIF output
on Diamond Monster Sound MX300 should be activated. If it doesn't
work it could be because your MX300 has a different SubSystem ID 
(this file includes 0x3001,0x3002,0x3003). This file is based on 
driver release 2048.

This file was sent to me by <chris496@pacbell.net>,

For information on how to build your own S/PDIF output for the MX300,
please visit http://www.algonet.se/~cyrano/






Below is a description of all the other changes made to this file:








Hacking the 2048 Vortex-2 Win9x Driver
======================================

I've modified the AU30MMED.INF file to reflect some of my personal preferences. Perhaps you will find this useful as well. Simply copy the appropriate file to the \Driver\Win9x directory and reinstall the drivers. Here's a line-by-line description of the changes made:
 
line 447) Turn on the "Select HRTF" and "Speaker Calibration" links in the Vortex Control Panel.
 
476) Use PCI List (www.entechtaiwan.com) to find the Subsystem ID and Subsystem Vendor ID of your audio card. For example, for my Diamond MX300 they are 0x3002 and 0x1092, respectively. Enter the IDs for your card here in little-endian format to enable the S/PDIF output, if it isn't already enabled.
 
499) Enable the PC Beep playback channel. The PC Beep channel on the SigmaTel 9708 codec powers up in an unmuted state and needs to be explicitly muted by the driver. Otherwise, an unmuted channel could (theoretically) contribute noise to the output.
 
516) Maximize the master-volume slider. This initializes the front- and rear-output gain stages to 0 dB (unity). For the best SNR (signal-to-noise ratio) performance, leave the master volume at the ceiling (unless you're using headphones) and adjust the ambient volume at the external speakers.
 
521) Maximize the volume sliders for the digital sources; set the gains for the analog sources to approximately 0 dB. The SNR of a digital signal is greatest when it exercises the full range of the DAC (digital-to-analog converter). Any setting below the maximum attenuates the digital sources and reduces SNR. Each 6 dB of attenuation subtracts one bit of resolution. The gains for the analog sources are set in a middling position to give good performance and to allow one enough range to customize the mix to his/her desires.
 
523) Maximize the Line-In, StereoMixer, and MonoMixer record sliders. There are two different gain blocks within the record path: (1) A fixed, source-specific gain is applied in the analog domain before the ADC (analog-to-digital converter); and (2) via the record sliders, an adjustable gain/attenuation modulates the data from the codec in the digital domain. In my opinion, this is a poor method to implement a record channel. To maximize SNR, the sliders should control the gain in the analog domain so that the magnitude of the incoming signal matches the digitization range of the ADC. If a weak input is coarsely recorded by the ADC, a gain in the digital domain does nothing to restore the lost bits of resolution. Likewise, if a signal clips in the analog domain at the front of the ADC, a subsequent digital attenuation doesn't recreate the original waveform; you are simply left with a smaller version of the distorted signal. Until Aureal corrects this, I've set the analog and digital gains for these three channels to 0 dB. Use volume controls outside the record pathway to set the amplitude just below the ADC's clipping threshold. (See lines 525, 568, 569, and 576 for the further execution of this philosophy.)
 
525) Maximize the Line-In voice-recognition slider.
 
527) Maximize the Mono Out volume control. Like the master-volume slider, the top rung corresponds to 0 dB.
 
530) Mute the PC Beep channel.
 
531) Select Line-In as the default recording source.
 
532) Select Microphone as the default voice recording source.
 
533) Mute Mono Out.
 
551) Set the maximum playback gain for the Telephone channel to 8 x 1.5 dB = 12 dB. More gain allows one to boost weaker signals to a comfortable level. However, it is also easily possible to drive a signal to distortion. If a channel starts clipping, ease back on the accelerator. With power comes responsibility.
 
553) Set the maximum playback gain for the Line-In channel to 12 dB.
 
554) Set the maximum playback gain for the CD-ROM channel to 12 dB.
 
555) Set the maximum playback gain for the MPU-401 channel to 12 dB.
 
568) Set the analog gain for the StereoMixer recording channel to 0 dB.
 
569) Set the analog gain for the MonoMixer recording channel to 0 dB.
 
576) Set the maximum digital gain for the Line-In recording channel to 0 dB.
 
593) The Mono Out mute state mirrors the Telephone mute state, and vice versa. When the modem header on the MX300 is connected to a capable telephony device, this is convenient in speakerphone and answering-machine scenarios.
 
598) By default, show the Telephone and Microphone playback channels.
 
599) By default, show the Telephone, MPU-401, and MonoMixer recording channels.
 
613) For the Analog EQ Channel, select "None" by default.
 
865) Default to 64 wavetable voices.
 
Feel free to mix and match, or study the changes and come up with your own customizations. Although not done here, you can disable the DOS SoundBlaster support (and preserve precious resources) by removing the semicolons from the front of lines 145, 146, and 147.