If you want better sound, you may not want an AC-3/Dolby Digital option. While the AC-3 soundtracks on laserdisc might have 6 discrete channels, processing of the uncompressed digital soundtrack on your laserdiscs with the new Dolby Pro-Logic II decoder may be better. While not discrete, there are no compression artifacts like those in AC-3/DD (10 to 12:1). The digital soundtrack can be decoded full range in all of the Pro-Logic II channels (unlike the original Pro-Logic that limited the surround channels to 100Hz-7kHz and the center to >100Hz -- on most processors) and the new steering logic (front AND rear) is almost as good as having a discrete soundtrack.
For what it's worth, I compared some laserdiscs that I have to their DVD versions. While the quality of the picture improved, the quality of the audio went downhill. And to make things worse, I was comparing a Dolby Pro-Logic decoded soundtrack (the original, not the new II version) to their Dolby Digital counterparts.
Of course, the above comments are based on my experiences and yours may be different. But if you still want to take a step backwards , here's a link for you.
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