I've haven't done any kind of direct circuit comparison between these models. The 7000 kind of fits as a follow up to the 1000/2000/3000/4000/5000 series. The 3300, 3500 and 5500 just don't fit. You can find Sansui Brochure/catalogs from 1969 and 1975 on line. We need information between these point in time. I tried to upload a Navy PX brochure from the era in question but the file size is too big. It shows the 800 ($129), 1000X ($140), 2000X ($154), Eight ($258) and 7000 ($228). The 7000 gets a 1/2 page display, the others just get 1/4 page. The specs posted in this brochure don't comply to the FCC requirements so this brochure was published before May 1974.
To put these prices in perspective, the $129 800 in 1973 dollars is equivalent to $733 in today's money. The $258 Eight would be a whopping $1,466 today. Also keep in mind these prices were well below retail. This stuff was seriously expensive in it's day.
- Pete