home theater question. 6 ohm speaker/8 ohm receiver?

I pretty sure that the 605 is certified for 6 ohm performance. I have the 606 and I know it has 6 ohm performance. So yes, those speakers should work.

There is no such thing as an "8 ohm" receiver.

All receivers can handle 4, 6, 8 ohm speakers.

So you can compare receivers - the BIG NUMBERS printed are usually for 8 ohms, but the manual or details should include power for 6 and 4 ohms as well.

You just have to be careful using speakers closer to zero ohms because this draws more current and causes more heat. So be a bit cautious about cranking the volume and make sure you have LOTS of space around the receiver for venting and you should be fine.

The power amplifiers in the receiver output so much power.
Power is the product of Voltage times Current.
If you load an amp with lower impedance than it's rated at, for the same voltage that the amp is outputting there will be a higher current. But if you reduce the voltage (by reducing the volume) then the current will be as it is for the rated impedance.
Summarizing: Limit the Total Power that the amp i handling by not exceeding the volume.
Of course, if you run loads lower than 4 Ohms, you may be exceeding the max current that the amp's output transistors can handle.
An additional note:
Speaker impedance varies with frequency. The nominal rated impedance is an average of that within the mid-range frequencies.
As an illustration go to http://www.churchsoundcheck.com/imp1.html
It doesn't hurt to learn a bit more about this technical details. It'll help you to make a more intelligent choice.

There is no such thing as an "8 ohm" receiver.

All receivers can handle 4, 6, 8 ohm speakers.

So you can compare receivers - the BIG NUMBERS printed are usually for 8 ohms, but the manual or details should include power for 6 and 4 ohms as well.

You just have to be careful using speakers closer to zero ohms because this draws more current and causes more heat. So be a bit cautious about cranking the volume and make sure you have LOTS of space around the receiver for venting and you should be fine.

The power amplifiers in the receiver output so much power.
Power is the product of Voltage times Current.
If you load an amp with lower impedance than it's rated at, for the same voltage that the amp is outputting there will be a higher current. But if you reduce the voltage (by reducing the volume) then the current will be as it is for the rated impedance.
Summarizing: Limit the Total Power that the amp i handling by not exceeding the volume.
Of course, if you run loads lower than 4 Ohms, you may be exceeding the max current that the amp's output transistors can handle.
An additional note:
Speaker impedance varies with frequency. The nominal rated impedance is an average of that within the mid-range frequencies.
As an illustration go to http://www.churchsoundcheck.com/imp1.html
It doesn't hurt to learn a bit more about this technical details. It'll help you to make a more intelligent choice.

There is no such thing as an "8 ohm" receiver.

All receivers can handle 4, 6, 8 ohm speakers.

So you can compare receivers - the BIG NUMBERS printed are usually for 8 ohms, but the manual or details should include power for 6 and 4 ohms as well.

You just have to be careful using speakers closer to zero ohms because this draws more current and causes more heat. So be a bit cautious about cranking the volume and make sure you have LOTS of space around the receiver for venting and you should be fine.