I am selling my MODIFIED BI-AMPABLE Matrix 804 floor standing speakers for $1,100. I had these modified at SG CustomSound so the speakers could be actively bi-amped. At the same time I had the capacitors replaced by hand matched top of the line Jantzen and Solen capacitors. I ran the mids and highs off a Jolida 50 wpc tube amp and the bass off a HCA 1200 Parasound solid state amp. The resulting sound was musical magic! the midrange and highs were warm and musical while, the bass, with its own amp comes through powerful and smooth. The soundstage and imaging are outstanding. The modifications alone cost $700.
To bi-amp these speakers you will need an electronic crossover. I used the Marchand XM9L which I am selling in a different post.
I must caution you that the speakers are not in the best cosmetic condition. I have taken pictures to emphasize their flaws. Also the grills will not stay on without new pegs.