If you are not receiving "synergy" then either the sound signature is not your thing or your reference material is not geared towards the K712 Pro.
Here are a few tracks that I really enjoy with mine. Give them a listen. The K712 Pro really does not do well with heavy rock, but just about everything else sounds great as long as it is recorded well.
Armik: Casa de Amor, Flames
Marcus Miller: Renaissance, Detroit
Peter Murphy: Love Hysteria, Time Has Got Nothing To Do With I
T.H.White: The Private Spotlight, Separations
The Doors: Essential Rarities, Queen Of The Highway
Thanks for the reply. It's not that I feel I'm missing a certain synergy (just trying to better define and understand it), but I suppose I'm more curious to what everyone's preferred setup is.
My current amp/source inventory was purchased largely because I got good deals on the Aune T1 and the O2 combo. Plus I could roll tubes on the T1. Cheap fun that works with a wide variety of headphones. Now it may work, but that doesn't translate into a good pair with, again, synergy. I don't think I'm a big fan of the O2 and K712. The T1 seems to be a little better, but the amp on the T1 isn't all that great.
Currently, I brought the O2 and K172s to work and I'm using Google Music. Some of the music I've uploaded is a variety of mp3s and some FLAC. I'll try to find those tracks and see what I think. I'll listen here, then bring the cans home and try those again with the T1.