One speaker I would look at in this range are some
Pi Fours with upgraded drivers and a nice wood finish. You could get a set of three for $5k. They will have far greater dynamic range than Salks or KEFs or anything else mentioned thus far. They can look nice and hit THX Reference levels at your listening position, which is not something any of the other speakers will be able to do. The advantage to this even if you aren't interested in high output levels is they will have zero distortion at anything other than crazy output levels. Totally clean sound as the drivers are just breezing by. They measure
very well on and off axis, and they are a easy load for any amp so your Onkyo would be more than enough to get great performance out of them, no need for a separate amp. Take your amp money and get another subwoofer. I would recommend two subs, not for loudness, but for a more even sound across your listening area, ie more accuracy and a better sound. Two subs also do a lot to defeat subwoofer localization, where the sub draws attention to list position and messes up the sound stage. At $2k, I would go for a
pair of VTF15h subs if you like it loud. If you need something with more WAF, check out a pair of
ULS-15 subs. I would also bee looking at a pair of
Rythmik E15s as well.