The Z-9 is without doubt one of the heftiest receiver in its class, in term of size and weight. It's certainly as flexible, feature-laden and as future-proof as can be(What will i do with 9 channels at the moment?).
But let me just state my criticsm of it. Not so much on the receiver, much less from listening to one, as I am sure it's impressive alright. What follows is my distress at reading its technical specification on power rating. I hope i am wrong, but based on what little I know, the Z9's technical write on power is anything but candid. It appears to be more a marketing hype than anything.
(1) Overstated output power
Downloading the Z9 brochure, I was disappointed by some of its misleading and useless power rating. The brochure claims a 300w/channel power using 4 ohm loads at 1Khz. I really find this spec a product of dimwits. Why would anyone bother to listen to music at only 1khz???? What's the point of this spec? And measured at 4ohms? Check the back panel of the receiver just beside the speaker terminals. It has this very revealing caution: MIN Speakers: 6 ohms. So why measure at 4ohms when you can't listen to it with 4ohm loads???? Totol BS.
After measuring at 4 ohms and 1 khz, there another section that says it delivers only 170w/channel into 8 ohms 20h-20kz. That would seem more realistic. But check again.
Looking at the electric power consumption, it says 1,000 watts. How a 7-channel 170 watt/channel amp plus 2 channel 50watt presence channels, plus preamp circuit (say 50watts) can give out a total of about 1300 watts when it consumes only 1,000 watts is so beyond me that any technology behind it must be worthy of a Nobel prize for Physics!!
(2) Inadequate and Misleading Dynamic Headroom
The receiver is supposed to give an instantaneous peak power of 210 watts into 8 ohms. That's rather pathetic. If the continuous is 170 watts, you get less than a 1db headroom. A piano or drum being struck requires around 1.4 times the continuous power rating during the first few milliseconds, assuming your volume setting is already in that continuous power level. If the amp can't hack it, the drum or the piano at that level will sound muffled and constrained. But i am sure the receiver can hack it at much lower volume levels.
Lastly, those other dynamic headroom figures apart from that in the 6-ohm load are totally useless. The receiver cannot handle loads below 6 ohms as cautioned at the back. This is NOT a high current amp as blatantly advertised. The fact that the user is cautioned against using any load lower than 6ohms betrays this. NO high current amp has such a caution. NAD can drive 2-ohm loads, Rotels and Harman kardon, likewise, though 4-ohm loads are stated minimum.
I have nothing against the receiver. In fact, I wouldn't mind having one.
Most likely this amp can give no higher than 120 watts CONTINUOUS into 8 ohms cleanly, ALL CHANNELS DRIVEN. That should fall within the ambit of its electric power consumption. But there's be very little power left from which to drive instantaneous peaks CLEANLY. Still an adequate power for the average listening room.
The suspicious rating used by Yamaha seeems to be no different from most other Japanese brands like Pioneer and Onkyo which have no qualms overstating their power with gusto. Using DIN or JETA standards is a nice way to overstate a rating. Nothing in the tech spec states that the rating was measured with ALL CHANNELS DRIVEN. It is very easy to extract the most numbers when only ONE channel is driven. Which is probably what Yamaha did for the Z9.
My caveat is not with the receiver. But with those marketing gurus at Yamaha who must have muscled into the technical guys' better judgement to make an impressive amp unnecessarily more impressive by overstating power ratings. What for? The better to mislead unwary and uninformed customers? Seems these people have no confidence in their otherwise excellent products.
