recommend speaker for Krell KRC and KSA-200S

Just bought a set of used Krell gear from audiogon and now looking for set of speaker go with Krell. I am interesting in used speaker and budget is around $6,000. Speakers will be placed in the game room 15x30 upstair with one side rail open looking to downstair. I want bass, vocal, and soundstage. Main music is slow rock...

Any suggestion would greatly appreciated,

Thanks.