Wiim Ultra output voltage

[Malte74]

Hi everyone!
I have a Wiim ultra with a couple of power amplifiers connected to it (one for the front and one for driving two large passive subwoofers). I have no issue with the output input matching, no hiss on idle and no distorsion from overdriving amplifier inputs but I'm curious which, in theory, should be the best output voltage between 1V or 2V.. I understand that lowering output to 1V cost some SNR but since I do most of my listening with the volume between 30-50 (50 is loud..) with 2V and 1V lets me use much more of the volume (50-75/80) I guess I can take some of the lost SNR back in that end?
Is there an argument for one being better than the other? When listening and comparing 2V might, just might, be a touch meatier and more dynamic while 1V might, just might, win on clarity and soundstage but since I have to adjust volume to what is close enough between the two everytime I switch is not exactly A/B so it's hard to tell. I know I should listen and choose what I prefer and that is what I'm doing (2V just because it changes volume quicker when using the tv remote in hmdi-mode) but I'm here to learn and I repeat the question: Is there some technical reason to why one of the options would be better, even If inaudibly so, than the other?
Regards/Martin

 

[hipoagumol]

As long as your amplifiers are ready to receive 2v input signals (if they are modern, they do, if they are vintage then maybe not) then 2V is the correct choice of out voltage for Ultra as it maximizes SNR earlier in the audio chain.
Copilot put in more technical wording:

At the output of the Ultra's DAC:

• 2 V gives you ~6 dB better signal‑to‑noise ratio than 1 V
• This is because the analog noise floor stays the same, but the signal is larger

This is why higher line levels became standard in hi‑fi over time (CD players settled on ~2 Vrms).

2 V reduces downstream gain requirements
With 2 V:

• Your power amps need less gain to reach the same loudness
• Less gain means less amplification of their own input noise and distortion

This is especially relevant with:

• Multiple power amps
• Long interconnects
• High‑sensitivity speakers or subs

So on paper, 2 V wins.

 

[Valentino]

What is the sensitivity of your amps? Check specs.
I always recommend setting the Ultra output voltage equal to or below the amp’s specified sensitivity. Thus the amp cannot clip, even with the ultra volume at 100%.
Worth noting that above 50% 1% change equals appx. 0.3 dB, so at 50% you’re at -15 dBFS.

 

[mlsstl]

The way I do.it is to use the output voltage that gives my loudest desired listening level at about 75% to 80% max volume. That leaves a bit more still available for softly recorded material and also leaves plenty of volume control range when I'm not listening at my max loudness. (I find it annoying when I hit my loudest desired level at 30% or 40%)

 

[Malte74]

The amps are apart audio champ 2. Specs say that on rca input it's 10Kohm 1V 0dbfs. They have weird gain controls. Even at 1V I can have them set to minimum and still get enough volume. The difference between minimum and maximum are pretty small. More importantly I hear no strange thing on 2V and gain on maximum. No hiss, nothing that resembles input overload-related distorsion.. It just works.
This is my usual problem and the reason I posten the question (it's been floating around some swedish forums for a while now..): One says this, someone else something else..
What is more important for sound quality? Being able to use more of the volume control or the 6dB loss in SNR? SNR is pretty good on a Wiim Ultra so are those 6dB:s even audible?
A bit strange that with the wiim set on 2V and the gain controls on the amp on full I get no deteriation in sound quality (I'm a relatively experienced listener).. It should distort like crazy but it just works, and works fine..

 

[Deleted member 29222]

...
A bit strange that with the wiim set on 2V and the gain controls on the amp on full I get no deteriation in sound quality (I'm a relatively experienced listener).. It should distort like crazy but it just works, and works fine..

This has been my experience as well.
As a side note, I noticed that when I decrease the output voltage of the Wim ultra, my subwoofer becomes more prominent in the mix. It acts almost like a loudness?

 

[hipoagumol]

According to specs this amp has input sensitivity 0.775v or 1v, I find diverse dara. So it is initially designed to give its maximum gain for that input level, hence you should feed it with signal <=0.775v)/1v
Reason you can't hear any clipping or distorsion is because that amp also has advanced protection circuitry (APC) that prevents clipping it by dynamically adjusting gain and reducing signal input peaks. More detail here
However the best signal quality you can get of it and also volume range at the output is to make it work as designed.
So my advise is then to adjust the wiim ultra output voltage to 0.8v-1v


Regards

 

[hipoagumol]

By the way I found the manual and there's a Led that lights when this APC feature is working. So In theory with ultra output set to 2v you would see it ON very often while with proper input voltage it should stay all the time OFF, meaning the protection is not acting on the input signal to adapt it, which is the ideal situation.

https://pa-systems.ru/media/catalog/item/1000/580/CHAMP-2.pdf

 

[Malte74]

Running 1V now.. Sounds equally good but normal listening now is in the 60/70-range instead of 40 something.
Are those 6dB:s of SNR something to worry about? One initial plan was to use 2V and compensate by having the gain controls low..but they make such a small difference.
I agree on the subwoofer out, I have to cut output by 2 to 3dB when using 1V but maybe the subwoofer out is unaffected by the voltage-setting?
"hipuagumol"
I have never once seen the apc led come on.. I've played yello and infected mushroom with the gain on full, volume 70 plus and 2V output and things were moving around in my 45m2 livingroom.. Just the green led.

 

[Valentino]

IIRC the Ultra’s noise level lies at something like -115 dB at 2 V, so no, you will not hear those 6 dB.