Cary still only lists these including the Grayhill switch. A local colleague did additional upgrades on mine beyond the std stuff Cary offers. The newer upgrades were better imo than the older F1 upgrades. The newer Mundorf caps really made a difference over the older Jensens too on my buddies 98 pre. He had both versions in his preamp too. I sold mine, will see I if I can find the name of the upgrades volume potentiometer etc. Cary does not offer it iirc.