No, I haven't heard any of those. What I did have in my system over the past 2 months were the ARC LS26, Classe CP-700, Herron VTSP-1a/166, and the Ultraverve. The LS26 is probably the comparison you are interested in: the LS26 was a little less warm in the midrange (with a Tung-Sol black glass in the UV), a bit more clarity, perhaps a tad deeper soundstage. For example, percussion in orchestral music came across clearer with the LS26, and sounded a bit more vibrant and real (also with piano). I thought the low end was similar on each preamp. Overall, I preferred the LS26. The ARC is at least 3x more expensive on the used market and definitely was no where near 3x better. Maybe like 3-4% in my system: the UV2, if the sound is what you are looking for, is well along the curve of diminishing returns. Still, I wouldn't mind owning the LS26!