Good Speakers for Rock and Roll Under 15K

JBL 4367 would be at the top of my list. Dynaudio active monitors would also be a consideration. Vintage JBL, 43xx line, would knock your socks off if you can find them in original condition. 

Volti or JBL, but also a second amp; solid state.

Might also audition Yamaha NS5000s. Have heard them once for a bunch of hours driven by Gato equipment (preamp and monoblocks), mostly playing rock and they sounded glorious.....I've just never heard them in my system

Speakers are such a personal thing; so, my only advice for you is to: 1) demo as many speakers as possible 2) trust your ears 3) be open minded 4) have a consistent plan when it comes to "your" demo music.

If you decide to pair a SS amp with a tube preamp (a good strategy in my book), then take a close look at amps from CODA. 

Dynamics and transients are key characteristics in producing lifelike sound. I never heard an 86db speaker excel at these, no matter what amp / amps were used. Keep in mind, rock and roll recordings are generally very compressed, compared to classical and jazz, at least ime. If you just want loud, you really need high sensitivity speakers. And if you want control, you need good ss, at least with the power amp. The louder one wants to play, the room plays an important, constant part of all this. My last point. A good system as described above, does not care what music is playing. Enjoy ! MrD.