Here's what I've thought about and learned since the last post.

I don't remember what source you're using, but I would THINK DD2.0 tracks or similar lack lower end frequencies (because they intend you to use a .1 channel for anything really low.)

I can't prove what the cut off is because I don't have access to an official DD 2.0 soundtrack of SW.

My RtW preservation uses PCM from a laserdisc rip. Here is a frequency analysis of ANH:

As you can see there is definitely low frequency there.

Here's a close up below 200Hz:

Now here's the deal, boosting the lower end is still not a good idea. In fact the LFE is suppose to be mixed 10db lower in volume. (Home theaters are calibrated to play the LFE track back 10db louder to compensate.)

Modern stereos have Pro Logic II or better. If the frequencies are there, it will use them. DPL2 upmixes properly to 5.1. The work is done for you.

That's also the problem. Not everyone has DPL2 in their equipment. Older Pro Logic means 4.0 surround upmixes.

So what do you do if you don't want to use the space on a DVD for PCM or assume that everyone has DPLII or better? Transcode it yourself.

http://forum.doom9.org/showthread.php?t=83384 is a great guide (though a bit out of date since ffdshow can now output directly to an ac3 file).

I was going to provide a sample of how this works, but I've got PowerDVD problems (which is the what I was using in the chain to encode the DPLII).