richard:
i'd troll the usual sites like audiogon, and the big Meridian dealers to see what they have used. no clue about europe though.
if you want to go 96/24, that's gonna get pricey. non-upgraded 6000s are a lot less expensive. a pair just sold on eBay for $7K. there's a pair on audiogon right now for $9K.
i didn't do a 6000C because my setup won't physically deal with the vertical speaker. started with a 5000C and the 5500HC was a huge wonderful upgrade.
for me, music is most important, so the rears were just whatever was simple and reasonably sized (6Ks would be too big for my room there). i have a pair of 33s in the bedroom i've thought about swapping with the 5Ks in fact.
not sure i could justify 6000s all-around. i mean, Trifield is the shiznit, but what's coming out of the rear channel isn't what i'm paying for, IMO.
doody.