Phono preamp comparison/Pass,Herron,Avid

I am shopping for a new phono preamp to mate with my Basis 2500/Vector 4 arm combo. The cartridge is a Dynavector xx2 mk ii . I have narrowed my search to a Pass Labs XP-15, a Herron VTPH-2 and perhaps an Avid Pellere. Research in the analog forum reveals a couple of recommendations for the XP-15 and xx2 combo, but I have found no direct comparisons of the Pass and Herron units. I find very little on the Avid either but it is a newer unit. I would be interested in hearing from you if you have one of these units on why you chose it and how it impacted your system. I have Pass and Avid dealers in my town but neither has a unit to demo presently. If you are wondering what my goals are, at this price point, they are transparency, neutrality and low bass fidelity.
Thanks in advance for your posts.