One of my customers has owned Response 5s for several years. Good sounding speakers with good frequency extension. Contrary to what was said above, he uses solid state amplification to good effect, although they sound excellent with tubes as well. Many if not all the more recent ProAc models are lower impedance, generally in the 4 ohm range, so they are much less tube friendly, and that would include the D80.
$8500 is quite a bit more than the going price.
$8500 is quite a bit more than the going price.