Two powered subs with bookshelf speakers or two floor-standing speakers?

You can make bookshelf speakers with subs work, but it is harder to do.  Some like it if they are the type that wants way more bass than the artist put on the original recording.  I've heard one great system in this configuration using Raidho and REL, about $30k in speakers.  

Floorstanding is much easier to make sound good.

YMMV.

Jerry

it simply depends on too many factors to have an opinion on the generality

if there is a generality, it would be that well integrated subs always add to the quality of sound of most systems

in theory, you have more flexibility with bookshelf speakers and subs. In reality, it's much harder to get it right.

The easiest route is powered floorstanding speakers. But who wants it easy? 

It may depend on what you define as bookshelf. A 7” or 8” woofer can go low enough to make the sub truly a subwoofer. A 4” or 5” woofer usually cannot, so the “sub” is really covering a range into the midbass where its presence is more discernible and thereby harder to blend in. The other issue is placement. Not every room affords you the option of putting speakers where they can sound their best.  Having a sub can either ease or worsen this problem…

I’ve often considering going from two stand mounts, two subs (current setup) to two floor standers, two subs but I hesitate because my current setup sounds absolutely amazing as is and I also like having one of the two subs as a near field sub, just to the left of my listening position. Works great in my room this way. The other sub is in the corner behind my right channel stand mount speaker. My point is that bass is sometimes better dispersed in the room if you can play around with the sub placement rather than having it tethered to you speaker as it is in a floor standing speaker.