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Headphone Amp vs Standalone Passive Preamp

NotTheDroid

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Feb 13, 2023
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My current office system has a Schiit Modi 3 and a Schiit Sys, connected to a Rythmik L12 and a Hypex Ncore NC122MP power amp feeding Alon I speakers with an RCA splitter. All the RCA lengths are short, 6" to the amp and 3' to the sub. I'm considering swapping out the Sys for a headphone amp that also would function as a volume control for my speakers. I rarely use the second input in the Sys — really only when I pull out my DJ gear to practice — and don't mind just swapping cables when I do that. Is there any reason that using a headphone amp like the Topping L30, JDS Atom+, or Schiit Magni for speaker volume control would be worse than the Sys? Would one of those be better than another as a preamp? I sometimes swap between USB input and a toslink for the chromecast audio, but that I can do on the DAC. And yes, I know I'd be even better off using the DAC for digital volume control, but I'm kinda attached to a physical knob, the E30 only has a remote, and I'm not in a position to drop RME-style money.

Sidenote: all of that gear was purchased before I discovered audiosciencereview, and yes I did give myself a little pat on the back when I read all the love for Hypex and Rythmik here.
 
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NotTheDroid

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Following up here since no one responded, I couldn't find a solid answer elsewhere, and I figure I'm not the only one with this question: I swapped the Sys for a Topping L30. No noticeable degradation of sound quality, though I haven't run any measurement tests, and now I have a headphone amp as well. Though the L30 does stack more awkwardly over my Modi — I might end up getting slightly longer RCA cables so I can unstack them.
 

Nordling

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One thing you always have to check is the impedance ratio:
- between output impedance of the DAC to the input impedance of the (headphone-)preamp, and
- from the (headphone-)preamp to the power amp.
That ratio should be 1:8 to 1:10 or higher.
I know that the output impedance of a passive preamp is dependent of the volume setting, so that makes things difficult.
Btw I have used a Topping L30 as a preamp to a NAD power amplifier, and it worked great.
 
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NotTheDroid

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The numbers I found for impedance list the Topping L30 as "as low as 20" output and the ncore as 10kinput, Schiit Modi is 75 output and L30 is 2.5k input. So thankfully I'm way clear of those ratios.
 

ampguy

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Unless you need a headphone amp, the sys passive unbuffered attenuator volume probably can’t be bettered unless you’re looking for eq or balance capabilities. I want to get an a70 pro later this year, but have great preamp controls with dacs, power amps themselves, and cheaper headphone amps w line out sabaj a10h, although l30ii probably better.
 
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