All, my ModWrighted HAPZ1 including a Bybee rail arrived last Tuesday. I was out of town most of last week, so I only have about 20 hours on it so far. Keeping in mind Dan's admonition to give it a full 400 hours of burn in, I won't attempt to make serious judgements with only 5% of that time on the books. However, with a couple of good listening sessions under my belt, I would say that I perceive a reduction in grain and probably an improvement in sound stage depth. I can't really comment on resolution, dynamics, upper harmonics etc yet. You may wish to follow my thoughts in more detail on audiogon as break in continues and as I work through trying to develop an efficient protocol for transferring my extensive classical music library to the HAPZ1.
Time permitting, I may try to get a quick A/B with my modwright sony 5400 in at about 130-150 hours.
Thanks to Dan, Kirstin et. al. for their usual superb work and communication.