[Wuthoqquan]

I've got a Pure II+ (signal black) about three weeks ago. It has gone through some in-depth testing already, with my IEM (Fiio EX1) and headphones (Sennheiser Momentum, Hifiman HE 400i and Fostex TH-X00). I'm certainly more than happy about the performance and flexibility of this amp, however, I'd like to gather more opinions on the behaviour of the gain switch and the resulting impact on the overall background noise whenever sensitive IEM (Fiio EX1 in my case) are connected to the Pure II+.

It would obviously be the norm to set the Pure II+ to the lowest gain, if the intention is to connect sensitive IEMs to it! Indeed, at the lowest gain, there's absolutely no background noise at all that I could ever manage to detect, even without any music playing. The signal is simply noise free and the background silent and pure as it could ever be!
However, with the gain set to medium the scenario with my IEM changes completely, since with this setting there's an audible hum in the background, which may not be perceived with the music playing but absolutely discerable if nothing is playing yet. This background noise gets higher if I set the gain to high.

With my higher impedance headphones, even at the highest gain setting, there's no hum/background noise and everything is totally silent as expected. Therefore, it would seems that the hum is simply the consequence of the improper gain setting, which is above the level acceptable for a sensitive IEM.

Once again, I do understand that the gain setting is there for a purpose, and that IEMs should be listen to with the Pure II+ set to low gain - as advisable/normal. But I'd just like to get a confirmation that it is normal for sensitive IEMs to pick up this hum/noise when the Pure II+ is set to medium or high gain. As a further information, my current source is a Fiio X3 II, connected to the Pure II+ using the interconnect cable provided by Vorzüge. Many thanks!

 

[vrapan]

I would expect it to be normal, my Pure II + and CE6P exhibits some humming on the background on mid/high gain but there is no reason to set it to either. If I connect even my Philips L2 at medium gain I can hear nothing but can still get some humming on high gain. Again pick the gain setting that provides enough volume to drive whatever is connected and don't worry what happens at higher gain settings! 

 

[Wuthoqquan]

Many thanks for the swift reply!

That's really what I told myself yesterday, when I had the weird idea of testing the Fiio EX1 at the medium gain: "But why should I ever need to listed to the EX1 at a gain setting other than low?!?".

As you also noted, when connecting higher impedance headphones the situation changes - as expected - and the hum at the medium/high gain setting sort of disappears and everything gets silent/noise free again.

Many thanks again for chiming in with your own experience and providing more comments on the subject!

 

[crashtest33]

Thanks to you lot, I'm suffering serious wallet damage with prescription auditory heaven as the treatment. Seriously happy with my Pii+
I'm soon to be the proud owner of a CLAS as well as my hpp1 (mainly just to try and answer the $1M question of which is a better DAC) but I was interested in how the RSA SR71B in single ended output compares with the Vorzüge?
Has anyone owned or heard them both?

 

[shigzeo]

  I would expect it to be normal, my Pure II + and CE6P exhibits some humming on the background on mid/high gain but there is no reason to set it to either. If I connect even my Philips L2 at medium gain I can hear nothing but can still get some humming on high gain. Again pick the gain setting that provides enough volume to drive whatever is connected and don't worry what happens at higher gain settings! 

By 'humming' you mean 'hiss', right? Humming is usually power/ground related, while hiss has other sources. Hum can't be fixed by gain. It is bad bad bad. I've not heard hum in any PURE, past, present, or early. I have heard hum from a couple of portable triode amplifiers, and a number of mains-powered desktop amps and DACs.

 

[vrapan]

 
By 'humming' you mean 'hiss', right? Humming is usually power/ground related, while hiss has other sources. Hum can't be fixed by gain. It is bad bad bad. I've not heard hum in any PURE, past, present, or early. I have heard hum from a couple of portable triode amplifiers, and a number of mains-powered desktop amps and DACs.

Yes I mean hiss sorry not 'in' with the audio terminology. It is hiss that disappears depending on combination of gain setting and headphone/earphone plugged in.

 

[Tony1110]

Yes I mean hiss sorry not 'in' with the audio terminology. It is hiss that disappears depending on combination of gain setting and headphone/earphone plugged in.

If you're hearing hiss in medium or high gain that's because you don't need those settings for your IEMs. Stick to low gain and use the other settings when you're using headphones that warrant using them.

 

[vrapan]

If you're hearing hiss in medium or high gain that's because you don't need those settings for your IEMs. Stick to low gain and use the other settings when you're using headphones that warrant using them.

I know Tony, I was explaining to another member why he could hear hiss...

 

[Tony1110]

Sorry lol. I was trying to explain to that member too but I quoted you incorrectly.

 

[henkie196]

  By 'humming' you mean 'hiss', right? Humming is usually power/ground related, while hiss has other sources. Hum can't be fixed by gain. It is bad bad bad. I've not heard hum in any PURE, past, present, or early. I have heard hum from a couple of portable triode amplifiers, and a number of mains-powered desktop amps and DACs.

The Pure II that I had, had a definite ground loop hum if I listened to it while it was charging. Or if the DAP it was hooked up to was charging. That last one was pretty weird, I wouldn't have expected the DAP charging or not to have been able to make a difference.
 
To turn Wuthoqquan's question around, is there ever a reason to use the medium or high gain, if you get enough volume on the low gain?

 

[fiascogarcia]

 
To turn Wuthoqquan's question around, is there ever a reason to use the medium or high gain, if you get enough volume on the low gain?

I never had enough volume range to use the medium or high gain with iems.

 

[crashtest33]

I never had enough volume range to use the medium or high gain with iems.

D'you know what, I've always wondered this!
My pii+ seems to power my Focals and my Altone200s on ALL 3 gain settings with no hiss, no distortion and no reduction in quality whatsoever??!! Just a change in volume!
Is this a testiment to the Vorzüge or my majestic choice in cans?

 

[fiascogarcia]

D'you know what, I've always wondered this!
My pii+ seems to power my Focals and my Altone200s on ALL 3 gain settings with no hiss, no distortion and no reduction in quality whatsoever??!! Just a change in volume!
Is this a testiment to the Vorzüge or my majestic choice in cans?

Haven't heard your cans, but I'll go ahead and credit both!  

 

[crashtest33]

I always make sure I read on here. CAREFULLY.
But it seems most people have missed a trick.
The Vorzüge and the Focals are both overrated and underrated.
Everyone says they're amazing etc. Yet they look to other products. Don't get it??!
I haven't heard the SR71B yet but my Vorzüge destroyed everything else. And I've yet to hear a pair of <£700 closed cans that compete with the Focals?!
Hey ho. More for us.
Btw guys, my Solo and Pure are going in for anodising next week and I'm sold on RSA's champagne gold end plates w/british racing green boxes. Mmmmm

 

[henkie196]

  I never had enough volume range to use the medium or high gain with iems.

With IEMs, I was basically forced to use the headphone out on my DAP. Line out from the DAP and low gain on the Pure II, I'd need very fine adjustments to get from "can't hear" to "too loud". But if I'd use the headphone out, I'd be double amping, and what would be the point of that (aside from the colouration the Pure II(+) adds)?
 
At least with headphones (like the HE-560), I'd get a more or less workable range on the Pure II - between 7 and 9 o'clock. On low gain.
 
That's why I'm wondering what use one would have for the medium and high gains (unless you use the amp with the HO of a phone and leave the phone on a fairly low volume, I suppose).