Sure thing. I grabbed the local rep at GC one evening about a month ago. We used a Groovetubes GT69 and a Neuman U87 and tested an Avalon 737, UA610, LA610 and the 4-710d on vocals. I wanted to see the difference in all of them because I was thinking about the UA 610 for some tube color to my preamp base.
I was not impressed with the 610 on either mic. It was for lack of a better term "woolly" sounding. Just very rounded by also very grainy sounding. Next we tried the LA610 which was very similar. I have an LA2A so the LA side of the LA610 was not of interest. The 710d was extremely neutral sounding almost to the point of being flat. The tube control took it into the zone of the 610 that I had already decided was not something I could use. I was not impressed by either of the UA preamps for vocal. They might have won the day on instruments but not for vocals. We also tried the Avalon, which was warm but big sounding, clear, and the vocals were much more enhanced with both mics although the U87 was more polished sounding. The advent of the tube in the GT69 along with the tubes in all 3 models always seemed a bit too "tube" sounding. This mic sounds better with a transformer-based preamp. I have a Neve Portico 5012 which works much better with this mic.
I thought the 710 was akin to maybe Mackie mixer preamps on the normal side and even though it brought the tube on the other side, it was not impressive at that cost. I would rather take that amount of money and get a Martech or Avalon preamp.