Speaker Suggestions for ARC VT100

I am looking for suggestions on which speakers I should audition. Currentley I am using an Audio Research VT100 mk II amplifier with an Audible Illusions L1 preamp. I listen 90% to large scale classical (think Stravinsky, Mahler & Shostakovich). My room size is approximately 15 ft X 20FT. Price new should be no more than $6k. Hopefully making them used at about $3K or under. However, the cheaper the better!

Thanks in advance.