Forgot to share the following:
1) Ran the experiment of using the Micro-ZOTL as an integrated amplifier driving the Ulf's. It was great, just like on the DI's with the added benefit of more headroom/volume when needed! Again , this shows that the Ulf's are more efficient then the DI's.
2) Took the Micro-ZOTL out of the reference system and replaced it with a very good tube based preamp that I use in my second system to drive the 2A3 amp. This validated my assumption that the synergy between the Micro-ZOTL ( the powerful macro-dynamics-see through transparency-3D imaging-overall speed) and the Triode Lab 2A3 amplifier(gorgeous color/timbres-"meat on the bones" imaging) is what leads to the best combination for my ear's driving either the DI's or Ulf's. The system minus the Micro-ZOTL lacked the dynamics/life and sounded soft and took the aliveness out of the listening experience.
I wish all you DI's proud owners could hear this combination in your system, it will play at very high volume levels, is totally grain-less, accentuates the aliveness of the DI's/Ulf's, vivid 3D imaging and produces the most beautiful tonality/colors I have ever experienced.