Triangle Altea Esw amp recommendation

Greetings forum members! I am a novice and need help creating a descent system. I have a pair of Triangle Altea ESW speakers, an Oppo 105 player, and an Onkyo 706 SS receiver. My room is 15x20 feet. I listen to chamber, orchestral, jazz and classic rock on CD and SACD. The ESWs are bright and fatiguing with the Onkyo. I read that the Rega Brio is warm sounding for an integrated amp and may help tame some of the brightness. I also read that tube amps make an ideal (and perhaps necessary?) pairing for the bright Triangle speakers. I prefer to buy used and my budget is around $1000. I keep thinking that the ESWs could sound pretty good with the right amp! I am using standard speaker wire and RCA connectors. (I wonder if an upgrade in wire and interconnects would improve sound?) I would be very grateful for any help in improving my system. Thank you.