I have two M80 and 2 QS8 speaker and a Denon 1908 receiver. The Denon receiver was damaged last month so I am think about to replace it with Marantz SR6006 (it is on sale for $800 now). Anyone know if Marantz receiver has any issue to handle M80 (it is not officially rated for 4 ohm). I mainly listen to classic music and watch movie. I want to have the option to be connect to an external amplifier (like Emotvia XPA5) in the future. Any other recommendations are wellcomed.

Xiao, as always, the absence of an "official" 4ohm rating shouldn't be considered a critical factor. To get such a rating under FTC amplifier regulations the receiver would have to operate into a 4ohm test load at the full rated power for at least five continuous minutes. This is a severe lab test which would never be duplicated in home use. Full power occurs only at brief peaks(if ever)and "4ohm" speakers such as the M80 are around that impedance for less than half their frequency range.

The 6006 should have no difficulties at safe(to your hearing)listening levels and no separate amplifier should be needed.

If you're able to buy from Accessories4less, they have excellent deals on factory refurbished Onkyo, Denon and Marantz units at that price or less.

For what it's worth... I have a Denon 4311CI which does have a 4 ohm option. Even so the amp shut down on big peaks driving the M80s.

Specifically, the new Tron movie. At the beginning where the guy finds his dad's basement setup and is transported to the underworld. There is a big thump sound and that triggered the protection circuit every time (the sound level was up obviously). No such issues with the ADA1000.

Someone will be along shortly to explain to you why the 4 ohm setting does not do what you think it does. I'm a bit rushed and can't do it justice.

Here's the short version.

Dont' use the 6 or 4 ohm settings on a receiver. It's only there for government safety compliance. Receiver works better set to 8 ohms, regardless of speaker ohms.

The "4 ohm option" should never be used. It reduces the voltage output of the receiver's power supply section, with a resulting reduction in current and power because of Ohm's Law. This is done as a safety measure to reduce the chance of overheating with low impedance loads, but does so at the expense of maximum performance(lab tests show that maximum power is cut roughly in half). So, the result is directly contrary to "optimizing" the receiver for 4 ohm speakers, which some imagine to be the purpose.

Hmm, that's exactly what I thought the 4 ohm setting would do. The reason I chose 4 ohms was to reduce the possibility of amplifier overload. I realize that this would result in a reduction in output power but my primary concern was to avoid over loading the output stages causing a potential amp failure which could quite possibly damage my woofers via a DC current from a blown power transistor. Man that was a long sentence

Do you run the M80's full band? Not that it matters now because you have a proper amp to drive them, but with the right source material, peak LFE content is what will usually cause immediate protection shutdown with an inadequate amplifier for the job. Just curious, did you try that scene with the higher ohm setting?

Shutdown, if caused by overheating would be during sustained use over a period of time and would not happen at a repeated single point.

You sir are absolutely right, yes in fact I had full band set for the fronts, I forgot to mention it. And the peak LFE was the cause of the shutdown. Nice detective work there.

I can't recall if I tried with 8 ohms but I don't think I did.

It's interesting though that even the almost top of the line Denon which supposedly can drive 4 ohms in reality cannot.

Oh, it probably can if it isn't in 4 ohm mode with full band speakers!

I don't think it would help much in this case. The higher ohm setting would just put you at greater risk to damage the speaker. The ADA's ability to power the fronts would help greatly here. Bass management would be even more ideal. There is a lot of LFE and not to mention midbass content that is present in the M80's usable bandwidth.

it seems your audio card was clipping on strong signals.

Bass management!?, as in reduce the Bass!?! Heresy! Speak not of such things again!

Hahaha! Bass management in terms of setting a crossover on the loudspeaker to optimize its usable bandwidth.

It would indeed be "interesting" if even the 4311 couldn't drive a 4ohm rated speaker, but that isn't the case. Less capable Denon models and similar models of other makes can and do drive the M80s without difficulty.

There doesn't appear to be an online 4311 lab report available, but the similar 4310 tested at over 200 watts into 4 ohms here .

It should be noted that any LFE in the movie wasn't reproduced by the M80s or powered by the 4311, but by the EP500 which handles the LFE channel, so any shutdown was due to other reasons. The maximum peak in other movie channels is 105dB, which would require about 100 watts, easily handled by the M80s and 4311.

Also, to clarify a point regarding the default higher impedance setting, the higher voltage output allows a higher power output(but still well within the speaker's power handling capacity)before possibly damaging clipping occurs. The default setting lessens the chance of the speaker being damaged.

My fronts are set to Large and I have the Bass setting to LFE+Main. The Denon shutdown every time on large bass scenes. Of course I only tried it 2 or 3 times; I am not taking any chances with my stuff. I just switched the fronts back to small and bass to LFE. The funny thing was, that was just about the time Ian announced the new ADA amps. I had my order in soon after.

Yes, I do like my bass

Actually, I rarely play movies at really high levels anyway; the beauty of the system is that it still sounds great even at low volumes, which to me is even more impressive.

I can't wait till I replace my 10" Polk for a second EP500. Around Christmas I think, I even have a buyer for the Polk lined up:) I only wish it could have been an EP800 or two, but the wife does have her limits.