After CMI of Chicago bought Standel, Crooks designed the SG series amplifiers for that company.
Marks that can be entered for this maker: Transformer code.
Nothing predates 1972; components only push the date later.
Sold-price aggregates are not collected yet, so the archive gives no figure — condition, originality of the transformers and a documented recap move this model more than any list price.
Evidence: Vintage Guitar magazine