Hand me down audio equip- upgrade advice


First off, this might be my first post, but I’ve been admiring the Audiogon community for a while now. There’s a ton of helpful information that a lot of you have shared, and I appreciate that!

I’m lucky enough to have a boss who’s big into audio equipment, and handed down some of his older gear to me:

Benchmark DAC2 D
Classe CP-700
NuForce Reference 18 monoblocks
KEF 103/3 Reference w/ Kef Kube equalizer
Vandersteen v2w sub

I ended up having to refoam the KEF’s, but I have to say they are a great speaker! I’ve been enjoying this setup for about a year now, and want to explore some newer speaker options- preferably a floor standing full range variety. At this point, I’m fairly overwhelmed with the options out there- and looking for some wisdom.

I’d like to keep my first upgrade under $1500, with some wiggle room. I’ve been drooling over some Sonus Faber’s, but alas, I’m not ready to bite the bullet on anything in that price range (used, of course). KEF has plenty of lower to medium priced speakers, but I’d like to explore other avenues.

Thanks in advance
rillerr
What are you trying to gain? The only clue so far is "more robust". What do you mean by that?
+1 @millercarbon — We really don’t have much to go on here to make any meaningful recommendations.  What aspects of system and speaker performance are most important to you, and what would you most like to improve upon?  If you’re not sure what those things are yet, you should listen to as many systems as possible to solidify what you really like.  If you don’t have many dealers nearby, you might consider traveling to an audio show or two to see what really knocks your socks off and go from there.  FWIW, and best of luck in your search. 
I will venture a guess that your listening room has no acoustic treatments in it. I say this because most don't not as a slam. If I had the equipment listed, I would use at least half of the $1,500 for room treatments before I even thought about a speaker upgrade from the KEFs. In most set-ups without room treatments, 50%-60% of what you're hearing is the room and not the speakers. Just my $0.02,
That list is hand me downs? For f@$*s sake... Save some more cash and spend a little more on your next towers, the rest of your system can handle it. $3000 to $5000 opens up a lot of possibilities, especially on the used market. The $1500 market is a side step in my opinion. 
I agree with room treatment. I also agree that you have to spend more for a real speaker upgrade. I used to own the KEF 103/3 until I got the bigger and better (although older) 105 which I also restored. My 103/3 had the LF drivers refoamed and the donuts replaced. Fresh ferrofluid for tweeters. Crossover was recapped with Alcap from Falcon Acoustics. The KUBE also got new electrolytics. The 103/3 when properly restored are great speakers.