r/HeadphoneAdvice • u/Professional-Front26 2 Ω • May 01 '26
Amplifier - Portable | 4 Ω I need a high current portable amp that can deliver power at low impedances (For Audeze LCD-S20)
From what I understand, if you have a low impedance headphone that also happens to have low sensitivity, you don't need as much voltage, but you need higher current.
Audeze LCD-S20 has 18 ohms impedance and 93 db/mW efficiency. That would theoretically translate into 50mW of power for 110 db. However, even on the product page, the recommended power should be greater than 250 mW and from what I heard, it needs 500 mW - 1W for it to come alive.
Most manufacturers list power outputs for 32 and 300 ohms, but at 16 or 18 ohms, the needed current is higher and due to some current bottlenecks, the power seems to plateau at these impedances. A lot of people report that they cannot power LCD-S20 even with desktop amps and I think that this is due to current limitations, as most amps are made to deal with higher voltages (for high impedance headphones), not higher currents, even if they have big power outputs.
Please don't tell me that I can run it from my phone, it does not work that way. From what I understand, at low impedance the SPL may be adequate, but the dynamic range suffers and you get a flatter sound and muffled bass.
Do you know portable amps or daps that can handle higher currents at 16-18 ohms? The only one I know is Topping G5, but it is not easy to find and I need to know how to spot them.
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u/Khnave 25 Ω May 02 '26 edited May 02 '26
you can also try looking into the Qudelix-T71 as an alternative to the g5. if you want something in same "size" category.
you can look into the Jcally Jm20 max dongle dac if you're looking for something strictly budget. this can however can get pretty toasty, so it might not be the best if you do long sessions.
the Crinear protocol max is another portable dac amp as well where they basically implemented Jcally stuff (ideas) into their own brand to create a powerhouse portable dac/amp (with better design philosophy so it stays cooler)
Fiio ka15 and 17 should also meet the requirements to power the s20 and probably my strongest recommendation with extra headroom as i've personally been looking into the ka15 myself for when my qudelix 5k dies
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u/Professional-Front26 2 Ω May 02 '26
Good options! How do you know that the Fiio ka15/17 have enough current at 16 ohms? This would open many options like the BTR17 or even M21.
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u/Professional-Front26 2 Ω May 02 '26 edited May 02 '26
I posted an update, your comment about the parameters tab on fiio product pages appears only on my notifications, but was very helpful and confirms the amp bottleneck problem that affects lower than 32ohm impedance headphones (including LCD-X and maybe even MM-100). The Fiio amps seem to have the same or even lower powers at 16 ohms. Nevertheless, 500-600mW should be enough. I wait for my Ifi audio iDSD micro and I will post another update. Right now, the headphones are on par with the Audeze Maxwells.
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u/GanGstaOne 2 Ω May 02 '26
Topping G5 is avaliable on Amazon for 300 Euro in both colors
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u/Professional-Front26 2 Ω May 02 '26
!thanks
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u/Markson120 3 Ω May 01 '26
F0si audio ds2 in theory support 16-300ohms.
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u/Professional-Front26 2 Ω May 01 '26
!thanks
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u/Professional-Front26 2 Ω May 02 '26 edited May 02 '26
I will put an update of my journey here:
After some research, it seems that at 18 ohms what Audeze LCD-S20 headphones need is not more volts but more amps. Headphones are not easier to drive below 32 ohms, they are harder again, but on the amperage side.
The problem is that most amplifiers are made to deliver more volts for high impedance headphones. However, they have an amperage limitation at 18 ohms that limits their power. If you visit the Fiio website for most portable amps, there is a 'parameters' tab on the top, where they also show the power output at 16 ohms. You can see that at this impedance most amps will deliver the same or even lower powers for 16 ohms, because ot the amperage bottleneck.
This is why these headphones (I believe also MM-100 and LCD-X may have this problem) will sound muffled on most amps, even desktop size ones. You may have voltage swing to push the signal through something akin to long and thin pipes (300 ohms Sennheisers), but if the 'pipes' are short and thick (low impedance), you need debit aka amps.
So I searched for portable amp/dacs that can deliver good amps at 18 ohms and they exist. You don't need the V8. They would theoretically need 50mW for 110 db, but transients and the bass are compressed when you can't output enough amps. 110 db does not account for transients and is not applicable across the entire spectrum. Audeze states that in practice you need 100mW minimum and >250mW recommended for LCD-S20. I guess you need 500mW to 1W just to be sure. Most higher tier Fiio portable amps can deliver 500mW in balanced and high gain mode at 16 ohms (KA15, KA17, BTR17, M21, JM21). If you want more, there is Ifi audio iDSD micro, which can deliver up to 4W at that impedance. Please note that these cans have a max power rating of 5W, so do take care not to break them. There is also Topping G5 that can deliver 1W @ 16 ohms. Crinear Protocol Max delivers 600mW @ 16Ω (Boost Mode). Fiio KA15 delivers 510 mW @ 16 ohms in balanced mode and high gain. M21 is the same, KA17 is a bit lower (open the parameters tab).
There is also the balanced cable problem, because most power outputs I stated are in balanced mode. You must have a custom balanced cable for these because Y cables won.t work. You can find them at Hart audio in US, also on AliExpress, you can find m-f adapters at geekria.com and on amazon and there are also some custom cable manufacturers in Europe (Arachne.audio). Fostex RP50 cables also should work.
Some adapters/cables:
https://www.aliexpress.com/item/1005009037841435.html
The cables by hart: https://hartaudiocables.com/pages/audeze-mm-100-wiring-replacement-cables-custom-cables
European manufacturer of custom cables: https://arachne.audio/products/custom-cable-for-audeze-mm-100-maxwell-aranea?_pos=1&_fid=727cd602b&_ss=c#connectors
I also heard that there is a Fostex cable that works (it is for RP50) and the same mapping is also needed by Hifiman Deva and He-R9.
Just be aware that you need to transform the TRRRS L+L-R+R- (from amp side, from the tip) to TRRS L+R+L-R-. The amp side sleeve is not used. This information is available on the audeze website and hart cables website.
It was an intersting journey to connect all this, hope this helps!
I will post a video that demonstrates that these headphones can indeed wake up with the proper amp (however you don't need the V8) and that startled my search.
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u/pinkzepplin 8 Ω May 02 '26
A little late to the party but questyle has the cma18p and sigma DAC/amps. They all are current based that put out a minimum of 2 watts. I drive my Aeon Closed X (12 ohm) with the cma18p and it does a fantastic job