Bent Audio NOH passive is the one that I'm looking for. You can buy them direct for around $1500. Great reviews.
I believe it will work in true balanced mode. But having owned one, I liked the active mode the best. It had more life and dynamics. Things seemed to move faster. The passive mode did have a purer sound quality though. But I thought for my listening needs the active mode sounded the best overall. Rest assured. This is a great preamp!
I'd try something else. The design is pretty dated and IMO slightly veiled sounding in active mode and restricted in passive. But then again I only demoed the adcom for a week or so before moving on. My local dealer also stopped selling the Adcom line due to QC problems. The units like the "TVC" from Bent looks interesting from the standpoint of not having your output impeadence determined by the level of the volume control, but I have not heard one yet. However, it seems that "active" preamps are THE standard for even the most high-end of designers. That might say something.