So, after having the Acoustic Resarch SP-9 (I may be a purist, but…) in my system for about a week, then the Threshold FET Nine (Threshold FET 9 Preamplifier) for about a week, I finally did an A/B  comparison into my Maggie MG-12s – which are frigging PERFECT for my room (w/o tweeter attenuation) driven by the Nak PA-7.  The front end was reference quality vinyl and both preamps got proper warm-up  times..  The Acoustic Resarch SP-9 beat the FET Nine hands down (for my speaker/room combo anyway).  Subtle, but very significant differences.  Still need to do the A/B of the line stages with an SACD source, but the phono stage of that Acoustic Research is pure magic.