i want to connect 4 speakers of 8ohms to luxman a-311 i am confused because at the back its written A or B speakers 8ohms-16ohms A and B speakers min/16 ohms should i connect them normally or in series or parallel wiring
I think what that means is that if you want to run the A and B channels at the same time, you need a minimum of 16 ohms. If you were running A or B then 8 is fine. So, if you are going to run them both, wire your speakers in series.
I generally tend to ignore these rules, though. Just cause....
You need to be more specific about your intentions.
Four speakers total? Or four pairs of speakers?
If you are intending two pairs of speakers, then CM is esentially correct as far as impedance goes. If you are intgending four pairs of speakers, then you'll need an outboard speaker selector switch (see below).
Run all speakers simultaneously? Or each pair alone?
One pair of speakers alone can be 8 Ohm nominal impedance. However, not all 8 Ohm speakers are safe on your amplifier since "nominal" is not a very defining word and can be used by manufacturers to get out of telling the whole truth. Many "8 Ohm nominal" speakers have an impedance dip that is still unsafe for your amplifier. Pairing two sets of such speakers will cause your amplifier to shut down if you play at more than background music levels.
Do you have the speakers? Or are you buying new speakers?
If buying new, consult the manufacturer for low impedance dips in the speaker's measurements. If these are, say, new in wall speakers, the impedance dips are minimzed and you might get by with two pair running together at low levels.
You should do some investigative work with manufacturers before making these connections. It's possible the best advice is to bypas the switching in the Lux and use an outboard speaker selector with a protection device which raises the overall impedance seen by the amplifier.
With a panel rating of 8 ohms minimum, and not the phantom 6 ohms sometimes quoted, one pair of very easy to drive speakers at a time are what I would look at.
Assuming the impedance doesn't dip below 6 Ohms on your "8 ohm" speakers, which they are very likely to do, you can run one pair and no more without risking the amplifier's shutdown. If the levels are not above background music, then you could probably run both pairs together.
Amplifier manufacturers state warnings that are at times meant to protect their own interests. If you want to try both pair simultaneously, go slow with the volume increases and don't play bass heavy music. If the amplifier gets overly warm, shut it down.