SO if I'm looking at spending $900-$1200 on a used pair of speakers that soundstage well and are good at resolving detail, am I going to find anything better than my Snell JIII's or would I just be spinning my wheels?
I'd like to spend $1500 on the amp, $800 on the pre
IMHO, budgeting close to double what you spend on the speaker for amplification is slightly unbalanced. Try spending about the same amount or more for the speakers. I think it will get you further. Speakers are where the rubber hits the road so to speak. Differences between speakers are usually more marked than between different types of SS electronics.
The drivers in most $1500 to $3000 retail speakers cost under $100 for each speaker and are mass produced by third parties for use in many designs. Above about $3000 retail the drivers tend to improve dramatically as the labour, cabinetry, shipping and other basic raw costs flatten out and more $ is available to use better drivers. Essentially a lot of the first $1500 in construction cost goes into cabinetry and elegant veneers/finishes, which are especially expensive/time consuming but have a large impact on the look of the speaker, the perceived quality and sales. A good cabinet is of course extremely important in speaker design as is the choice of crossover but as the saying goes "you can't make a silk purse from a sow's ear".