Mixing speakers, 6 and 8 ohm?

With the controls for relative volume level on surround sound recievers the balance of sound wil not be a problem. As long as the front there are the smame or very similar the sonics should not be a problem. If your reciever is of reasonable quality the ability to run nominal 6 ohm speakers should not be a problem.

The differential between efficiencies coulds be an issue but probably no. Most Kefs are in the 91-93 db range and I don't know the specs of Quads. Usually the only efficeny issues are with speakers that are 8-10+ db appart.

Good luck!

You really should consider matching at least your front 3. You will never get a "good" soundstage or imaging without 3 matching. Rears are not as important.

Most receivers/amps can easily handle 6 ohm/8 ohm mixes. However, check your manual to make sure that your receiver can handle five 6 ohm speakers (since that will be a minimum rating to be safe).

Don't forget a good sub!

As long as your receiver can drive both 6 and 8 ohm speakers you will be fine. You will compensate for the impedance difference when you set the speaker levels - if you used different amps with different gains, it would be a different situation.

The issue with mixing speakers has more to do with the sonics of the different speakers, which has already been mentioned. The goal is a seamless soundstage throughout the channels, the most important being the fronts (LF, C, & RF). The rears are less important but they do work best if they match the fronts as well.

Hope this helps. :o)