Wellllll......it's tough to beat what Altec already did with the 19, that's for sure.
I never got the JBL setup dialed in to my satisfaction, despite it being a popular/recommended choice at AK.
The Advent combo sounds very, very nice. The bass is quite deep, and moved away from boundaries, not too full. I have since gone to a three way with those, using a Fountek ribbon above 10K. That provides the advantages of the horns (huge soundstage, excellent clarity, and very dynamic), and also the benefit of the ribbons (extended top end that seems to float free from the speakers).