Jon;
You are correct on the history of the Solarus. The combos were a bit weird because they looked like a 3/4-size version of their piggyback brothers, but were larger than most combos of the era which made them awkward to transport. Not much demand for these except from crazy Sunn collector geeks like me! Personally, I love the old Sunn tube bass amps. Last weekend I played my Hofner 500/1 through a Sunn 200S with a 2x15 Sunn bottom. Tone Heaven!
Ryan Phelps