Optimal line out level for WiiM Ultra + Audiophonics MPA-S250NC?

[Fralle]

Hey everyone,

For those of you using the WiiM Ultra with an Audiophonics MPA-S250NC (or similar Hypex-based power amp), what line-out level are you running?

I remember someone here once recommending 500 mVrms, saying that the “best” setting is one where the volume sits around 70 during normal loud listening and distortion starts somewhere around 90.

Just for fun, I asked ChatGPT, and it suggested the opposite – to set it at 2 Vrms for the best signal-to-noise ratio and overall dynamic performance.

So, what’s the general consensus among those who’ve actually tested both?
Which setting gives you the cleanest, most dynamic result — and why?

Thanks in advance!

 

[Ronnie D]

Just for fun, I asked ChatGPT, and it suggested the opposite – to set it at 2 Vrms

I don't have this amp; however, on the Audiophonics website, it states the following:

Input sensitivity Max Power at 1.66V RMS

So personally, I would use this value or lower.

The closest match, without going over on the ultra, would be 1 Vrms, so that would be my starting point.

 

[Fralle]

I don't have this amp, however on the audiophonics website it states the following
Max Power at 1.66V RMS
So personally I would use this value or lower.

Interesting. I am almost certain that Iv'e read several posts here stating a lower gain setting is actually better. Only problem is that I can't find the threads/post right now.

 

[Ronnie D]

a lower gain setting is actually better

Perhaps try out the settings and see which you prefer.
Just my personal preference not to go above the manufacturer's recommendation,

 

[Fralle]

Perhaps try out the settings and see which you prefer.
Just my personal preference not to go above the manufacturer's recommendation,

To be completely honest I am not sure my ears are good enough to tell the difference. And after the time it takes to switch between the settings and the match the volume it is almost impossible to say for sure which settings sounds the best.

I am more curious about the science behind all of this since I know that I have read about the importance of gain settings before.

 

[Ronnie D]

@Fralle . I think this may be one of the threads that you were thinking about

L

Thread 'Connecting Ultra to Amp - I prefer to use amps AMP IN input, but not many have that.'

Jan 9, 2025

At least for my use case i very much prefer using Ultra with amplifiers, that do have some kind of AMP IN input. The benefits:
1) Volume is controlled only by Ultra´s volume control
2) connect Ultra wth subwoofer (its LFE input)and use Ultra`s many SUB mgmt options, and speakers are relieved of playing low freq.
3) Sub is included into Room correction and speakers syncing
4) volume of subwoofer is matched with volume of main speakers

I tried also other scenarios, like connecting Ultra to AMP´s AUX IN input, and using on ULTRA FIX Volume,...but...

• lecko
• Replies: 12
• Forum: All things about WiiM Ultra

 

[Aquaman]

The two things you want are:

a) to have the amp to work at the lowest possible level
and
b) to have the volume setting of the streamer at about 50 or higher for normal listening, or in other words, if you crank it up to your max. listening level you want to be near 100.

So start off with the max. 2Vrms on the Ultra. Then set the gain on the amp to its minimum (does it have adjustable input gain?)
Turn up the gain on the amp until b) is reached.

If there is no adustable input gain on the amp reduce the output gain on the Ultra until b) is reached.

 

[Fralle]

(does it have adjustable input gain?)

Not on this model but on the more expensive versions of hypex/purifi based Amps from Audiophonoics you get that feature.

 

[Aquaman]

Not on this model but on the more expensive versions of hypex/purifi based Amps from Audiophonoics you get that feature.

Then take the second route. No harm done.

 

[More Watts]

Input sensitivity Max Power at 1.66V RMS

I'm confused now. Doesn't the above spec mean that the amp can reach full power with 1.67 volts input?

So, the only way to get the amp's full power is to set the WiiM to 2 volts output, correct? Isn't it impossible for the amp to reach full power at lower WiiM output voltages?

 

[slartibartfast]

I'm confused now. Doesn't the above spec mean that the amp can reach full power with 1.67 volts input?

So, the only way to get the amp's full power is to set the WiiM to 2 volts output, correct? Isn't it impossible for the amp to reach full power at lower WiiM output voltages?

That's true but will you be playing at full power? If 1V is more than loud enough at maximum volume then you know the amplifier will never clip.

 

[More Watts]

That's true but will you be playing at full power?

I did not realize that people did not use their amplifiers to full capacity. But then I live in the boonies and can 'crank' my system. I can see where this can be an issue for apartment dwellers and others. Thanks for the info.

 

[Fralle]

I did not realize that people did not use their amplifiers to full capacity. But then I live in the boonies and can 'crank' my system. I can see where this can be an issue for apartment dwellers and others. Thanks for the info.

Also for people like me with a 250w power amplifier and a 2 year old running around the house.

 

[Fralle]

The two things you want are:

a) to have the amp to work at the lowest possible level
and
b) to have the volume setting of the streamer at about 50 or higher for normal listening, or in other words, if you crank it up to your max. listening level you want to be near 100.

So start off with the max. 2Vrms on the Ultra. Then set the gain on the amp to its minimum (does it have adjustable input gain?)
Turn up the gain on the amp until b) is reached.

If there is no adustable input gain on the amp reduce the output gain on the Ultra until b) is reached.

With this in mind then 500 mVrms is the way to go. Could you please explain why you recommend this?

 

[Aquaman]

With this in mind then 500 mVrms is the way to go. Could you please explain why you recommend this?

One wants to amplify as little of the incoming noise as possible and also to keep the distortion of the amp at a minimum. Thus —> a)

In order to support this you start with a high gain output voltage. —> b)

So far the theory. In practice you will neither hear any amplified noise nor any amp distortion if you don‘t drive things to the max.

With your amp you don‘t have a choice anyway. So it comes down to adjusting your output to a level that will give you a practical range for the volume control.

 

[Aquaman]

With this in mind then 500 mVrms is the way to go. Could you please explain why you recommend this?

Even though I was familiar with the general concept I have now dug into it a little deeper. Also to cross check with my settings and amp.
So I just learned the math.

Taking your specs here is what I get:

Amp: Audiophonics MPA-S250NC
Power rating: 250W into 4ohms
Gain: 25.5db --> 18.8x amplification of the input voltage

Assumed speaker impedance: 4ohms (you didn't mention that)

Max. ouput (into 4ohms):
Imput voltage 0.5Vrms: Volts to speakers: 9.4V --> 22.1watts
Imput voltage 1.0Vrms: Volts to speakers: 18.8V --> 88.4watts
Imput voltage 2.0Vrms: Voltst to speakers: 37.6V --> 353.4watts (this would drive your amp into clipping)


With your chosen setting of 0.5Vrms output on the Ultra the 22watts may seem low but it's the norm. In normal listening we're only using approx. 3 watts.

 

[Fralle]

Even though I was familiar with the general concept I have now dug into it a little deeper. Also to cross check with my settings and amp.
So I just learned the math.

Taking your specs here is what I get:

Amp: Audiophonics MPA-S250NC
Power rating: 250W into 4ohms
Gain: 25.5db --> 18.8x amplification of the input voltage

Assumed speaker impedance: 4ohms (you didn't mention that)

Max. ouput (into 4ohms):
Imput voltage 0.5Vrms: Volts to speakers: 9.4V --> 22.1watts
Imput voltage 1.0Vrms: Volts to speakers: 18.8V --> 88.4watts
Imput voltage 2.0Vrms: Voltst to speakers: 37.6V --> 353.4watts (this would drive your amp into clipping)


With your chosen setting of 0.5Vrms output on the Ultra the 22watts may seem low but it's the norm. In normal listening we're only using approx. 3 watts.

Thank you for taking the time doing this. But it is 8 ohm speakers in this case. My bad for mixing up the specs earlier, since it is actually 150 watts into 8 ohms. Does that mean 1 Vrms is the way to go?
.

 

[slartibartfast]

Thank you for taking the time doing this. But it is 8 ohm speakers in this case. My bad for mixing up the specs earlier, since it is actually 150 watts into 8 ohms. Does that mean 1 Vrms is the way to go?
.

It is easy to try it and see for yourself.

 

[Aquaman]

Thank you for taking the time doing this. But it is 8 ohm speakers in this case. My bad for mixing up the specs earlier, since it is actually 150 watts into 8 ohms. Does that mean 1 Vrms is the way to go?
.

Just for you I restarted my PC. Sorry, can't do it in my head:

 

[Aquaman]

Does that mean 1 Vrms is the way to go?
.

No, if the listening level is fine, stay there.

When I said earlier that 22w are within the norm you have to put this into relation with the speaker impedance.
So now 11w are fine.