Hi XLR_Silver!
I'm very happy to tell you all of your worries and conjectures about subwoofers are untrue; well at least from a REL + bookshelf's perspective.
Let me elucidate my point...
1. Contrary to your belief, bookshelf + sub combo is generally easier to place optimally compared to floorstanders. You see, in floorstanders, moving the whole cabinet to find the sweet spot makes prompts you to move all of the drivers (since they're in the same vertical housing)! Sounds like the highest you can achieve is merely a possible compromise for the midrange and bass response. Unlike in the former, you can start by moving the bookshelves first to find the best midhi presentation. Once you've found it, you may proceed by moving the subwoofer to all possible locations within the room to find the perfect bass performance. Ergo, Perfect location for the midhi presentation coupled with a perfect location of bass (for the sub) equates to perfect overall performance! Afterall, listening to the complete music spectrum that the human ear is capable of hearing (20,000Hz down to 20Hz) is truly of orgasmic proportions!
2. REL does not require you costly interconnects. Instead it has a pre-supplied speaker cable (10 meters) which you can cut to desired length once you have both found the "best" location and the sub reached full break in status.
3. To get the fastest & most tunefull bass, REL subs are best connected via speaker level connection (hence from the power amplifier's Left/Right speaker outputs). Therefore, it can be connected to ALL kinds of amplifers; unlike some other good subs (like the M&K MX-350 or MX-5000THX) which can only be connected via line level (from the preamp); big problem if you only have an integrated amplifier.
If you still doubt this theory, try to contact these fellow Pinoydiophiles and audition their sub/bookshelf systems:
1. Hyperion (Sonus Faber Electa Amator + REL Strata 2)
2. Russell (Sonus Faber Concertino + REL Q100e)
3. Dogears (either Axiom M3ti or NSM Model 5 + REL Quake)
4. Racio (Sonus Faber Guarneri + Sonus Faber Gravis sub). Although this is not a REL sub, but Racio guaranteed me that his sub sounds like a REL. hehe. (yon pala, eh ba't hindi ka na lang nag REL Bai? gulo! ...hehe)
5. Jay_Cee_Em (Spendor S3/5 + REL Q150e)... driven by Plinius 8150 integrated amp (naks special mention of his amp pa!)
6. Yours truly (SF Concertino + REL Strata 3)