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L30 II and Aune X7S comparison. Output impedance effects on different types of headphones.

ROTUND_Catto

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May 13, 2023
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So I have this new amplifier aune X7S(2021 version) and here at asr it was measured to have rather high output impedance(about 11 ohms). But I also have a topping L30 II with me and I wanted to sell one of the amps so I compared their sound on the single ended outputs with the Hifiman HE400SE(28 ohm planar), Letshuoer S12 Pro(16 ohm planar), Final e500 and e1000(16 ohm dynamic driver) and samson SR850(32 ohm dynamic). I did volume match them with a microphone. Now from my impressions the aune has much better bass definition and also extends deeper into the sub bass(with planars as well) and is also less sibilant than the topping L30 II while having better vocal clarity as well and the drums kick and slam harder as well. I dont hear any hum or noise either at low volumes even on my IEM. Basically the aune is the clearly superior amplifier in every way even on the 6.5mm output. Is it possible to measure the voltage swing capability of an amplifier somehow? Maybe when the music calls for higher current( like when big drums hit) the aune can deliver more current than the topping? I thought the aune would sound worse than the topping because of higher output impedance and lower power rating on single ended but yet its clearly superior, not from a tonal but TECHNICAL perspective and I am confused about the science behind this since planar magentics should not be affected tonally by output impedance and the output power on the aune should be much lower as well. I have ordered some xlr adapters and cable and when they arrive I will try to see which of the 2 amplifiers have higher maximum volume( by measurements it should be the topping). But I wanted to ask if this is because of the effects of output impedance or is it because the aune has much faster transient voltage swings than the topping? I know that planar magnetic drivers do not suffer from any tonal shift when driven by amps with higher output impedance because they have this "flat impedance curve" but I wanted to ask why is it so? why does output impedance affect a low impedance dynamic driver but doesnt affect a low impedance planar driver headphone? I tried to google the reason and I found this old research paper in a reputed journal discussing about this "transient distortion" for high feedback amps like the topping. ( https://ieeexplore.ieee.org/document/1162117 ) but I dont have the technical expertise to understand it but would love to get the gist of it.
 

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ROTUND_Catto

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Just to clarify I am definitely not mistaking higher distortion for more detail. Both the topping and aune have measured to have inaudible harmonic distortions to begin with. The aune is more detailed in the sense I can hear new instruments( like another piano, electric guitar or a bass line in electronic music) which I could not hear with the topping before. I am certain that distortion doesnt sound anything like a piano.
 
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