proac response 4 and 5

Years ago I had an opportunity to listen to a pair of Proacs driven with a pair of Cary 805c's. The system sounded incredible. I can't remember if the speakers were response 4 or 5's. Can someone tell me which model was the better of the two and what the retail on these were, and possibly some sonic differences between the two. Thank you
I also had a huge crush on Response 4 which is like a Refrigerator size(I remember as around 65" tall???& 250 pounder each) at my friend's back to a couple of years ago. I still don't forget the sound which I regard it as the best(to my ears) so far. He said $18000... I haven't seen 5 yet but it's smaller than 4 a lot but slightly bigger than 3.8. probably around 50"tall? Hope this helpful & happy listening!
as far as I know Response 5 was $14000.