Meanwhile, back at The Topic...
IMHO, if I had a room that big and $10-15K for amps and speakers, I would probably try this: I would call John Strohbeen at Ohm Acoustics, and ask if the Walsh 5000 would be able to work in that large space. If so, that's $6600 for the speakers. If your space is too big for them, John will tell you the truth. They work well with reflective surfaces, so you may not have to do as much to treat the room and those windows as you might with more directional speakers. They also have several frequency band output level controls, which might be especially helpful in your situation. For an amp, lots of clean power is the key. I would go for the Arion Audio HS-500 monoblocks, which are tube/Class D hybrid designs that output 500 watts each. I have heard them with both Nola speakers and Magicos, and they are great amps, IMHO. I had the RS-500 monoblocks (with solid state input stage) for a while and thought they were also pretty good. But the hybrids are better sounding and within your budget. That's another $6300 for the pair. That leaves you a bit left over for some decent power and speaker cables. YMMV, of course, but both of these products are sold direct with in-home trial periods.
IMHO, if I had a room that big and $10-15K for amps and speakers, I would probably try this: I would call John Strohbeen at Ohm Acoustics, and ask if the Walsh 5000 would be able to work in that large space. If so, that's $6600 for the speakers. If your space is too big for them, John will tell you the truth. They work well with reflective surfaces, so you may not have to do as much to treat the room and those windows as you might with more directional speakers. They also have several frequency band output level controls, which might be especially helpful in your situation. For an amp, lots of clean power is the key. I would go for the Arion Audio HS-500 monoblocks, which are tube/Class D hybrid designs that output 500 watts each. I have heard them with both Nola speakers and Magicos, and they are great amps, IMHO. I had the RS-500 monoblocks (with solid state input stage) for a while and thought they were also pretty good. But the hybrids are better sounding and within your budget. That's another $6300 for the pair. That leaves you a bit left over for some decent power and speaker cables. YMMV, of course, but both of these products are sold direct with in-home trial periods.