I've tried both direct and dipole rear speakers, and prefer dipole. Diffuse and enveloping is what you want for the surround channels. This is especially true if you have to live with non-ideal placement of the rear speakers. (This opinion relates to movie soundtracks; I don't have any...
To me, the ideal is to run all speakers full-range and use the subwoofer for the LFE signal only. This is, after all, how 5.1 was originally meant to be used.
I wonder what the current practice is among soundtrack engineers for using the LFE channel. Is there any logic to it? Or is it completely at the whim of the engineer? (I know, what difference does it make? Well, I'm just curious).
One word: used. You can buy high quality good-as-new speakers on the used market for 40% or less of original retail. Of course, assembling a matched set of HT speakers is more difficult this way (especially if you insist on a center - I don't use one myself). But the price/performance can't...
Expensive speakers are almost always large, with lots of drivers, capable of high SPLs and deep bass. Bigger is not neccessarily better, however. Depends on the room and what you want out of the speaker.
A level shifter, well, shifts levels. For example:
Link Removed
or
http://www.rane.com/bb22.html
No doubt there are others.
These are passive transformer-based devices.
When going from a higher to lower voltage (pro to consumer, not the case here) a simple attenuator can be used rather...
This is a general issue with interfacing ANY consumer equipment with ANY pro equipment. You have to use a voltage level shifter (NOT AN AMPLIFIER! Sheesh whoever told you to use a RadioShack amp is an idiot) to convert up to pro levels.
The THX specifications are secret, of course. If they were public then the THX label would have much less value, since an unlicensed product could (truthfully) claim to meet THX specs. Less money for George Lucas, in other words.
The LFE channel has a bandwidth of 120Hz, so any processor that uses the "standard" bass management described (correctly, as far as I know) by Harold, with a crossover less than 120Hz, is indeed throwing away part of the LFE channel. Not what I would call good bass management. (Of course, the...