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JDS Labs Atom good pre-amp for ICE125ASX2?

raistlin65

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MRC01

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What I like most about the JDS Atom, and would also make it a great preamp, is that in low-gain mode (which you would likely use as a preamp), it maintains clean signal even when you turn the volume down to low-medium levels. It is among the best 50 mV SNR that Amir has measured.
 

Berwhale

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The amp you link to has a volume control on it. What do you need the pre-amp for?
 
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raistlin65

raistlin65

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The amp you link to has a volume control on it. What do you need the pre-amp for?

This for a desktop setup where I already use the JDS Labs Atom as my headphone amp connected to my DAC. Perfer to use the volume control on it for both headphones and speakers.
 

Berwhale

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This for a desktop setup where I already use the JDS Labs Atom as my headphone amp connected to my DAC. Perfer to use the volume control on it for both headphones and speakers.

It will work fine. It's kinda similar to my setup. I have an Atom with JBL 1 Series 104 monitors attached to the pre-amp out. The 104's have an in-built class D amp + volume control. Listening volume for my headphones has the Atom volume around 12 o'clock. I set the volume on the 104's so that they're at a reasonable volume when I unplug the headphones. This avoids surprises and much fiddling with volume controls.

This setup may not be completely optimal from an SQ perspective, but I doubt if I could hear any difference and it's the most usable setup for me.
 
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raistlin65

raistlin65

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Maybe I asked the wrong question. I've read that the the Icepower needs a low output impedance from the input source. For example,
I've added a potentiometer at the input of the amplifier, and it turns out that the input impedance of these ICEPower amps drops significantly with rising frequency. At DC, the input impedance is 270K, at low frequencies, it drops to about 27K, and at 20KHz it's below 6K. This means that the amp needs a low output impedance source to drive it
https://www.diyaudio.com/forums/class-d/192789-icepower-125asx2-measurements-mods.html

Does the Atom preamp output have the right output impedance?
 

Berwhale

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raistlin65

raistlin65

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Yes. The output impedance of the Atom is 0.1 Ohms which is very small compared to the input impedance of the Icepower (even at high frequencies).

That's the headphone amp output, right? Is that also the DAC output via the RCAs?
 
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