What to upgrade next?

I think Onhwy61 makes a great point.

You seem happy with the sound. And, if you are interested in upgrading, I would ask what area(s) does it lie? From there, we can offer suggestions in terms of pushing your system in the desired direction. It seems as if your source, preamp/power amp, and speakers are on the smooth and warm side, while the cable is on the detailed and fast side. May just balance extremely well, and not need upgrading at all.

I can't argue with addressing the room, it's often the most overlooked link in the chain...

Out of all the suggestions so far I would tend to agree with Bidkidz. I myself have went through a number of power
conditioners,cables,power cords,digital upgrades. And while
they have all made nice Improvments in the sound, Changing
or upgrading speakers in the line you already have will
make the biggest difference.

Upgrade the room. It will make more difference than replacing the whole system. Most sonic annoyances are created by the room, not the system. I have found the information available from Rives to be incredible. Check out http://www.rivesaudio.com and see what they have to offer.

Yes the room treatments and set up are also key, sorry I left that out (stupid me)but in the end the speakers will limit the system sound to whatever they are capable of. The system sould change significantly with Vandy 5As versus all the treatments that I know of. Depth in my system became more real when I used a speaker that was capable of adding lower bass and extened highs. Treatments are a key system concern too.

Happy Listening.

Remember, a speaker will never reproduce what doesn't get there from the front end, therefore all things being equal speakers are the least important componant in your system. No speaker will have a good spectrum of sound, good imaging or soundstage in a bad room.

Mediocre speakers can sound good in a great room, but great speakers will only sound mediocre in a bad room. Treat the room and you will have a better stereo.