Ok, so I am back from my trip and I have spent a good amount of time with the little dot (though only burned in for 30 hours or so), finally running in "true" balanced mode with my HD650s and TADAC, and I am completely floored by the difference balanced makes for the HD650s.
Before my trip, I was using some cheap $10 microphone XLR cables that I found out a few days ago were not "true" balanced. They were just microphone cables with XLR connections--> Guitar center guys are idiots. I swapped them for some $50 Monster Audio Balanced cables while I wait for my Straightwire Encore IIs to get recabled for balanced.
I did a test over the weekend for SE vs Balanced. I was using the direct-tube to RCA out of the TADAC to SE into the MK6 vs. tube to opamps to XLR balanced to MK6. I swapped back and forth several times for many songs, and this is what I noticed, WITH THE HD650s only (YMMV depending on your cans) :
1. The HD650s sound like totally different headphones when balanced but still maintaining their dark signature that I love so much about them. My ears can't stand any harshness even for a minute.
2. All the instruments and little nuances in the music that were lost or drowned out in SE are brought forward in balanced mode for you to enjoy. I heard things in songs I have not heard before (I know you have read that many times on head-fi, but damn did that statement ever hold true).
3. Bass is improved like I have never heard on the HD650s. VERY controlled, not flabby at all. The best part is, you will only hear the bass when the music calls for it.
4. Instrument separation is also vastly improved along with the soundstage. Big improvements in both of these when compared to SE.
5. When I was swapping back and forth between SE and balanced, SE sounded like the music was rushed, and balanced sounds like each instrument takes its good time to present itself, but never feeling slow. Hard to describe, but I just got involved in the music more when it was balanced.
6. And another reason why I know balanced is a keeper, my wife actually hijacked my system for 6 hours on Sat. She has heard every upgrade to my system (because I made her listen), but she never cared to listen for more than 5 minutes. When I asked her if she noticed any difference when she heard balanced for the first time, all she said was, "Ummm..., I can't tell, but I just enjoy it more now than before."
I am completely sold on the Balanced camp with my HD650s. I spend so much time with my system over the weekend and never got tired of it. There are certain songs that just blow my mind. The songs that have music going from your left to your right, then back around -->, these types of songs just sound amazing in balanced mode.
I still have to roll my 5998s and Mullard ECC35s, send the TADAC in to get 2 Moon HDAMs installed, burn in everything for 300 hours, and waiting on my straight Wires and a custom made headphone cable from Fidelity Audio that I am dying to hear.