Hi - I used to own the Response 4's and frankly they were one of the most disappointing speakers I have ever owned. I bought them and sold them for $9,000 USD's. They absolutely MUST be driven by tubes ( preferably triode ) and they MUST have a big room - they need to breath. I would think that the 5's might actually be a superior speaker - I own 3.8's right now, and I love them, much more musical IMHO, than were the 4's. just my honest opinion. (p.s. I have never heard the 5's)
