Ok, that makes some sense. Super feed forward was the tech in use on the integrated amps concurrent with production timeline of the second Z series (the 3900-9900Z being the first Z series). I've had almost no exposure to models with super feed forward designs at this point, odd as that is.
Historically, my interest in Sansui was initially limited to roughly the 1974-1978 era. As I collected more gear, I expanded the time range in both directions, first going with newer models up through 1982 or so, then later going back into the late 60's and early 70's to a limited extent. The lions share of my gear is still heavy on mid to late 70's, so 9090DB, QRX-9001, G-9000, AU/TU 717/ 919 and related matched accessory components as well as definition and professional series gear.
Post 1982, I have some odds and ends but there are large gaps in my collection especially in receivers beyond the 9900Z, which is the newest receiver I own presently. Naturally, I kind of regret selling the Z-9000 years ago now, but live and learn, right? I own nothing newer than early 1986, pre-logo change gear at this point, so that gives you a better idea of what I have and don't have for comparisons sake.
Not to derail the thread further, but I've looked at the numerous debates on the eight versus eight deluxe here in the past and don't feel I have a straight answer on the winner in that contest. Many insist that the original eight was better as they threw a lot of engineering at it on a "cost is no issue" basis.
Others make the claim the eight deluxe is better as it is a newer model benefitting from improvements in technology. Now, advacement in amp tech came rapidly in that era, so that even a year would result in noticeable improvements, or so goes the reasoning. I've not owned either model, which again represents a pretty big blind spot in my collection as it can rightfully be said the eight constitutes a key moment in Sansui's development history.