this is the correct way to treat the LF of a multi-channel audio system.

i've played electric bass for some 36 years. any recording of electric bass is done DI, whether live or in the studio. though i appreciate someone's desire to use stereo bass reproduction (though the choice of good source material is relatively small), and i really don't care what sort of matrixed synthesis of the original source someone may prefer to design, manufacture or use at home (unless it was MY recording), i don't see the requirement of 2 outputs for redirected bass. nevertheless, it costs next to nothing to implement, so why not?

the really important thing is the discrete LFE output to it's own system of filters/slopes/delay/sub/amp and level control. as soon as you understand the potential of the 6th channel, you know that you shouldn't just sum it with redirected bass.

the demand on a sub is drastically reduced for movie formats. add a HP filter and you have a full range channel for dvd-a/sacd. use a LP point and slope that best suits LFE while not destroying the critical adjustment needed to reintegrate redirected bass. significantly reduce intermod distortion. ease placement problems by reducing the size of the subs. have a 'musical' sub and a 'movie' sub in the same system. be able to calibrate the LFE in relation to the redirected bass levels...on-the-fly if need be. invent new instruments. and, yes, even matrix the 6 channels instead of 5.1 (for those who like such things ) into gozillion.1 without changing anything but to add an LFE output. any one of these points warrants the output. it costs nearly nothing. lexicon is right for doing it and the 3 points they bring up to justify it (less demand, level adjustment and separating it from derived bass) are dead-on correct.

one more thing...once you've 'enhanced' my bass lines, promise you'll stop there and not compress, add reverb or flange or run your subs 6db 'hot'??