Thiel with that front end ouch! Really depends on what type of sound are you looking for. Here is a good primer
I'm in the wideband high efficancy camp and love it. Zu Druid and DHT 2A3 for me. They are in your price range and will slam with your Denon yet provide a terrific upgrade path. I've had 10 amps before finding paradise, every thing from Pas Aleph 30, tri path, pp el34,audiozone gainclone, tried mosfet ss and now pp2a3 Melody which is really special. Me I'd go for the Summits. Vintage JBL is like have investment in gold. Those Summits will fill your room with 10 watts. The Joesphs are nice but very different. Not my cup of tea. Life like dynamics is, for me the key. I saw a pair of Klipsch Cornwalls for 375 in Honolulu, a few upgrades and a nice 20 watt tube amp and presto! Your speaker budget alone would cover a whole system. But and a big but, depends on what you like and want, it may take years of tinkering to find out. Heck I could easily live with some quad 57 and Quad ll amps but I know I'd miss those big dynamic peaks I get with the Druids the Quads do other stuff that is very special, never ever heard a bad word on Quads. Heck in that room some Klipsch cornerhorns might sound nice, again with a good tube amp. And RSA, you are right the Joesphs quads or JBL summits, don't compare, the Thiels are just not in there league, a local dealer is always tring to push them on me and they just don't do it for me and everyone who loves them always says the same thing... " you just didn't have the right accompaning electronics" well I hope that the dealer could provide that, but no. Just do not have the involvement that comes with DHT tubes. Which can't be used with the Thiels. Now the Zu you can power off your cell phone and sound good( ok I've gone to far) really it all depends on what sound you are looking for and what future considerations are taken into account. Good luck and as always have fun with this crazy hobbie.