Does a sub need to be on the floor?

Under $5K for LRC speakers. Maybe under 3K even. The rest of my setup is to my liking except the receiver which eventually I'll upgrade. (marantz 5009, nad cd player, rega tt)

I've been looking at bookshelves like Spendor, PMC, dynaudio, .. I've liked most but I'm not hearing a really vivid imagining like I've heard with some maggies and other slightly non-conventional speakers.  So I'm kind of intrigued with taking a chance on ascend's ribbon tweeters.  I also need to hear the Linn 109's and a few others.  I liked the B&W 805 D3 but just can't afford them.  

Acoustic zen adagio jr .. Zu .. Too jmho 

There are a few things to remember about subs.  First, bass is largely a matter of moving air, i.e. pressurization and depressurization of the room. Listen to a car stereo to prove this idea with the car's relatively low air volume.  Second, most speakers cannot more air like a sub can since they usually have to be accurate on frequencies higher than low bass frequencies and large cone excursions will cause high bass and midrange problems.  I saw a review of a JL Audio sub where the reviewer felt its bass to be better than that of a Wilson Audio Maxx 2 Speaker, definitely a plumber of the low frequencies.  Third, a lot of speakers cannot produce the lowest bass or bass dynamics but sound great elsewhere.  Example-my single-driver speakers.  Adding a sub enhanced the one weakness of this design, IMO, bass dynamics.  And yes, it took some work.  A lot of where to place a sub depends on the size and dimensions of your room and where you sit.  As you move it away from room boundaries it will have less room gain but may sound better in other ways, particularly if it excites room modes less.  And a lot of recordings are primarily midbass that a sub will not enhance much unless you move its crossover point up into the midbass region, or at least have a slower low-pass rolloff.

I would agree with the reviewer of the JL Audio subs. I have a pair of E-110's I'm using with my Janszen hybrid electrostats and after some work to make them blend in well, they are incredible.

Doh, I meant to type:

"Quick answer, sure, you can raise it off the floor or even put it on furniture."

Best,

Erik