10-04-14: Dave_72
Ok, granted. However, you could biamp with a solid state amp on the woofers and a tube amp on the mids and tweeters. And not necessarily regarding full range, the big Tannoys, ATCs, and JBLs are full range at much less, so I dunno what you're getting at there.
What I'm getting at is that if you settle for 40-20Khz flat response in your main speakers, and choose wisely, you can get the same kind of sound quality in a $10K-20K speaker that would cost $70K-200K if you go for that 20-40Hz bottom octave incorporated into an all-passive speaker. The $30K KEF Blade is a world-class speaker ... down to 40Hz, as is the Sonus Faber Olympica at even less, as is the Magneplanar 20.7 at about $14K, and several others including the updated version of the Acoustic Zen Crescendo.
Imo, subs are cheating, and it takes forever to get them dialed in properly, and then you still have problems integrating them.
Cheating? By whose standard or law? I call it a cost-effective solution to an otherwise expensive and difficult problem. Integrating the newest round of subs is not that hard. My subs have continuous controls for crossover, 0-360 deg. phase, and volume. Newer ones add crossover slopes and room correction. I'd rather spend 1-4 hours integrating my subs than try to move 100-300 lb. true full-range speakers around to attain a balance between imaging AND linear bass response. In many cases, the room modes simply won't let you.
But with separate subs, you position the mains exactly where you want for soundstage and imaging, and position the subs at the best locations for linear bass response. Then you use the crossover and phase controls to integrate them. With some subs (e.g., the Velodyne DD+ series) you can further integrate with automated room correction. Use the Stereophile Test CD and a dB meter from Radio Shack and it gets even easier.
You can set up your rig any way you'd like of course, but just by hooking up a pair of subs and thinking that all is well is doing one a disservice.
I never implied it was that easy; that's your construct. I've posted in other threads that I take up to 3-4 hours to fully integrate my subs with the mains, but it's time well spent. Furthermore, with all the integration features that come with the best subs today, integration isn't a black art anymore.