Here would my choices. Just my opinion, but I do have extensive knowledge and experience with all these choices.
1. Parasound JC-1 Mono. These would be a little more than your budget used. Around $4000-$4500, but well worth the extra money.
2. Belles 350A Reference. Around $2500 used.
3. Odyssey Stratos Monos. Around $2000-$2500 used.
4, Parasound A21. New $2495, used around $1800.
5. Odyssey Stratos Plus or Extreme. Around $800-$1400 used.
You could look for a used SimAudio W5 or W7. The reviewer really liked the W7 with your speakers. Not sure how much they are used.