I know this has been beat to death...but i still have not found a definitive answer:
One main reason for that is because it is not that simple to come up with a definitive answer. For one thing, the preamp output can vary between 0 V to > 4 V for pretty much all Denon and Marantz AVRs. It is important to understand a few basic things:
1) The exact voltage measured at the output will depend on the volume setting, obviously at volume 0, the output will be basically 0 V, and at 80-82, or 0 to +2 in the relative scale, it would likely be around 2 V or higher, and may go up to 4 V or a little higher if you keep cranking it up.
2) The pre out performance in terms of "SINAD", or "THD+N, also varies with the output voltage, and therefore the volume setting as well. Take a look of the curve NTK posted on post#4:
You can clearly see that if you would accept 80 dB SINAD, that is 0.01% THD+N, then pre out voltage would be about 4.5 V maximum, and if you keep on cranking, it will drop to 55 dB, that is about 0.18% THD+N, still not widely accepted as "clipped" at that point, though technically speaking, for sure people like Amir (me too at that point) would consider that the output is clipping already.
So, you basically need to tell us what is the maximum THD+N, or minimum SINAD you would accept, before we can say what is the maximum pre out voltage you can expect.
A further complication is, depending on the design, and in this case D+M, as the pre out voltage increases, performance in terms of SINAD would vary as mentioned earlier, and it typically would drop quickly past a certain level, in this case, that level appears to be around 1.5 and then take another dive at around 2.0 V, when the internal amps are connected. However, when the internal amps are disconnected, in the so called preamp mode, the pre output would remain relatively clean, i.e. maintaining near peak performance in terms of SINAD, until the output voltage exceeds around 3 to 4 V.
In addition to the curve on post#4, you can also look at the one presented by D+M/Masimo:
In this graph, you can see that while it is true at at about 1.4 V, THD+N started to jump quickly, but you can also see that it would settle down when the output voltage reaches about 2 V at THD+N level of about 0.018% that is still low enough for transparency, and it really did not rise to 0.03% until it reaches almost 4 V.
So, the main difference between non preamp mode and preamp mode is not so much the output voltage, but the distortions plus noise level at the same voltage you pick on the graphs.
I want to use pre-amp out on my Denon AVR-X6700H (L/C/R) and also use the Avr's remaining internal amps for the remaining Atmos/Auro speaker array (11.1). When used in this fashion, the Denon's pre-amp output voltage (from what i have read) is 1.4-2.0 volts. Does this rule out the Buckeye NCx500-3 that has a sensitivity of 2.4-2.5 and an overall gain "below" 29dB? Also the use of XLR to RCA cables doesn't help. I have noticed that the Emotiva offerings specify a 29dB gain structure....but there DR3 offering is showing 2.4 v input sensitivity.....I am driving B&W 802's and want max headroom.....starting to think I have to buy a separate Pre-amp processor.
To be clear, in such a use case, you should set the X6700H to 13.1 configuration, so that you can use the amp assign setting to set the FL and FR to pre out, that is preamp mode. You don't have to do that and I doubt you can hear the difference, but since it can be done so why not.
This way, you can listen in 2 channel stereo at volume setting that will be high enough to drive those buckeye amp or Emotiva amp to their maximum without worrying about the voltage clipping.
I read the specs of the buckeyeamp NCx500, and i noticed if you use the Hypex "gain stage" he called it, the gain is 26.8 dB that's looks high to me but I am not going to argue as he's the one selling the amps (I would have thought it should be around 25.5 dB.
Still, to be on the conservative side, let's assume the gain is only 25.5 dB, you can do your own calculations and get the following output from the NCx power amp:
AVR-X6700H pre out voltage vs buckeyeamp NCx500 output Wattage based on 4 ohm load:
| Gain: | 25.5 dB | |
| | |
| Pre out Vrms | Power amp Vout | Power amp output W |
| | |
| 1.4 | 26.37 | 173.86 |
| 1.6 | 30.14 | 227.08 |
| 1.8 | 33.91 | 287.40 |
| 2 | 37.67 | 354.81 |
| 2.2 | 41.44 | 429.32 |
| 2.4 | 45.21 | 510.93 |
| 2.6 | 48.97 | 599.63 |
| 2.8 | 52.74 | 695.43 |
| 3 | 56.51 | 798.33 |
| 3.2 | 60.28 | 908.32 |
My suggestion, stick with the NCx500 if you want cleaner output than the Emotiva's.
