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JDS Atom Amp+ Review (Headphone Amplifier)

MJgooner

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I recently got some hd6xx headphones and I'm using an Atom Amp+ as my amplifier. I was originally content listening to music straight from the 3.5 jack on my motherboard (after EQing), but thought I could improve things with the Apple dongle dac. I believe it sounds better, but now I have to switch the Amp+ to high gain and turn the volume to at least ~2:00 to have a fun listening experience. This leaves very little headroom, and on some albums I've got to crank it nearly as high as it will go.

I know the hd6xx is a difficult pair to drive and I'm working against myself a little by EQing, but I thought the Amp+ would still have more than enough oomph. Should the addition of the Apple dongle dac really cripple the Amp+ this much?
 

pk500

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I recently got some hd6xx headphones and I'm using an Atom Amp+ as my amplifier. I was originally content listening to music straight from the 3.5 jack on my motherboard (after EQing), but thought I could improve things with the Apple dongle dac. I believe it sounds better, but now I have to switch the Amp+ to high gain and turn the volume to at least ~2:00 to have a fun listening experience. This leaves very little headroom, and on some albums I've got to crank it nearly as high as it will go.

I know the hd6xx is a difficult pair to drive and I'm working against myself a little by EQing, but I thought the Amp+ would still have more than enough oomph. Should the addition of the Apple dongle dac really cripple the Amp+ this much?
Damn, dude: You must have titanium ear canals. I just got a used Atom Amp+ and Atom DAC+ -- a classic stack -- and use with my HD 6xx, getting plenty of volume at 1 o'clock in low gain.

I've only used the Apple dongle DAC with my phone and easy-to-drive cans like the Meze 99 Classics or IEMs like the Moondrop Starfield, so I don't know how it affects sound coming from a computer. But it sounds screwy that a dongle DAC that measures as well as some desktop units would kill your volume that much. Either that, or your preferred volume matches that of a Top Fuel dragster at launch.

What are you using for your pre-amp gain for your EQ? Is it a big negative number?

Good luck!
 

phoenixsong

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Damn, dude: You must have titanium ear canals. I just got a used Atom Amp+ and Atom DAC+ -- a classic stack -- and use with my HD 6xx, getting plenty of volume at 1 o'clock in low gain.

I've only used the Apple dongle DAC with my phone and easy-to-drive cans like the Meze 99 Classics or IEMs like the Moondrop Starfield, so I don't know how it affects sound coming from a computer. But it sounds screwy that a dongle DAC that measures as well as some desktop units would kill your volume that much. Either that, or your preferred volume matches that of a Top Fuel dragster at launch.

What are you using for your pre-amp gain for your EQ? Is it a big negative number?

Good luck!
From the review measurements here it seems that the DAC+ outputs twice the voltage of the Apple dongle
 

MJgooner

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Damn, dude: You must have titanium ear canals. I just got a used Atom Amp+ and Atom DAC+ -- a classic stack -- and use with my HD 6xx, getting plenty of volume at 1 o'clock in low gain.

I've only used the Apple dongle DAC with my phone and easy-to-drive cans like the Meze 99 Classics or IEMs like the Moondrop Starfield, so I don't know how it affects sound coming from a computer. But it sounds screwy that a dongle DAC that measures as well as some desktop units would kill your volume that much. Either that, or your preferred volume matches that of a Top Fuel dragster at launch.

What are you using for your pre-amp gain for your EQ? Is it a big negative number?

Good luck!

Yeah, this is what im talking about. You're getting plenty of volume at 1:00 on low gain and I can crank it all the way up on high gain on some tracks. can this be right?

The EQ gain is -6.4 dB, nothing crazy?
 

fieldcar

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I know the hd6xx is a difficult pair to drive and I'm working against myself a little by EQing, but I thought the Amp+ would still have more than enough oomph. Should the addition of the Apple dongle dac really cripple the Amp+ this much?
I Tried this a long time ago when the JDS Atom launched and had the same experience with the apple dongle dac + a JDS Atom.

As @phoenixsong said, The apple dongle dac maxx'es out at ~1V, whereas a typical desktop DAC doubles that at ~2V. The 6XX is only hard to drive to loud levels on dongle dacs and other portable audio, but a well regarded $200 stack should drive it louder than you can handle. Just save up for that JDS DAC+ and you'll be happy.
 

pk500

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I Tried this a long time ago when the JDS Atom launched and had the same experience with the apple dongle dac + a JDS Atom.

As @phoenixsong said, The apple dongle dac maxx'es out at ~1V, whereas a typical desktop DAC doubles that at ~2V. The 6XX is only hard to drive to loud levels on dongle dacs and other portable audio, but a well regarded $200 stack should drive it louder than you can handle. Just save up for that JDS DAC+ and you'll be happy.
Very interesting. Yeah, buy the Atom DAC+ for around $100 new or $75 used, and you'll be cooking with gas, man. I love my Atom+ stack -- a lot of clean power and musical clarity for $200.
 

Jimbob54

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I Tried this a long time ago when the JDS Atom launched and had the same experience with the apple dongle dac + a JDS Atom.

As @phoenixsong said, The apple dongle dac maxx'es out at ~1V, whereas a typical desktop DAC doubles that at ~2V. The 6XX is only hard to drive to loud levels on dongle dacs and other portable audio, but a well regarded $200 stack should drive it louder than you can handle. Just save up for that JDS DAC+ and you'll be happy.
And even worse as @MJgooner im guessing is in the UK and might have one of the EU spec apple dongles even more hobbled to a few hundred mv
 

DaRo

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Hi

First of all...thank you for review. Im very noob in audio stuff. I read whole review but still wondering if Atom amp+ will be sufficient to drive headphones -AKG K240DF ? Specification of them say : Sensitivity 88dB, Max. Input Power 200mW, Rated Impedance 600 Ohm. Atom can deliver Max. 136mW .Can stand alone amp be the solusion or should I pick stack Amp+DAC ? What About Topping L30 (2V ~60mW), Is Topping real alternative for JDS in this case ? Im thinting to use this set with PC. Any advices ?

Regards
 

DarrylG

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Yeah, this is what im talking about. You're getting plenty of volume at 1:00 on low gain and I can crank it all the way up on high gain on some tracks. can this be right?

The EQ gain is -6.4 dB, nothing crazy?
You don't say so explicitly, but I assume you're using the Apple dongle as a standalone dac, connected to the Atom amp, right?
 

Weebster

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I recently got some hd6xx headphones and I'm using an Atom Amp+ as my amplifier. I was originally content listening to music straight from the 3.5 jack on my motherboard (after EQing), but thought I could improve things with the Apple dongle dac. I believe it sounds better, but now I have to switch the Amp+ to high gain and turn the volume to at least ~2:00 to have a fun listening experience. This leaves very little headroom, and on some albums I've got to crank it nearly as high as it will go.

I know the hd6xx is a difficult pair to drive and I'm working against myself a little by EQing, but I thought the Amp+ would still have more than enough oomph. Should the addition of the Apple dongle dac really cripple the Amp+ this much?
I have the EL DAC and Atom Amp (the plus is nearly identical). I also top out at about 1:00 on low gain, so that Apple dongle must be really crippling the system. I also have a MIYO which is an all in one USB DAC/amp. When I connect it to my windows computer I can listen to the HD6XX at a volume of about 24, but when using the same equipment on my Mac I need the volume at about 90 to get roughly equivalent volume. All that to say that a better DAC would substantially improve your setup.
 

adam2434

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Curious if folks are running the Atom DAC+ and AMP+ stack into powered speakers or into an amp with passive speakers.

If so, is that working well in terms of the AMP+ having enough clean output voltage to drive speaker amplifiers well?
 

zack20cb

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Hi all, thanks for all the great information. This is my first time posting, and I hope you'll forgive what might be an ignorant question.

I've been very with my Atom Amp+. I've been gradually dialing in a desktop setup, switching my headset back and forth frequently between two computers, and before I tidy it up with a little DIY breakout box with the ports in convenient places, I'd like the community's guidance on this question.

Is it OK that I'm bridging the ground pin of the amplified output to the ground pin of the 3.5mm TRS line in?

In my day-to-day setup, I run a headset with a TRRS plug (Philips X2HR + Vmoda Boompro). The natural way to do this, with a dedicated headphone amplifier in the mix, is with a pair of TRS to TRRS adapters before and after the amplifier, so that the microphone channel of the TRRS connection bypasses the amp. Here's a diagram of my setup.

xOEdEqn.png


I really like being able to switch computers with just one switch (a Sescom SES-TRRS-AB, it's basically a passive switch). I'm considering building a little box to cut down on the number of chintzy little adapters in my setup, but before I go to that trouble, I want to make sure that it's kosher to be bridging the grounds in this way. There's really no other way to connect everything, short of:

1. separating the DAC and the microphone ADC, and
2. moving away from the Vmoda Boompro and its TRRS connector.

In the current setup, if I silence my music and turn the amp way up, there's a bit of noise or interference, but it's well below audible at actual listening volumes; I would only ever notice it if I had the volume from the DAC cranked way down and the amplifier volume way up. I don't think this is ground loop interference (it sounds the same whether or not the microphone bypass is connected), but I thought this might be a well-defined question with a simple answer. Is it OK to bridge the grounds in this way, or is this not preferred?

If something here is unclear or misconceived, please let me know. I'm new to this whole space and it's pretty complicated!
 

AnalogSteph

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You have correctly identified the ground loop (which tends to be a bigger issue on the microphone side), but it's hardly surprising that you want to simplify things, Rube Goldberg would be proud of the current setup! ;)

You can probably understand why I like to keep microphone and headphone grounds entirely separate now. Combining them is trivial, but you can't separate them again afterwards without issues. In your case, you could liberate the Boompro mic by sticking it to the side of the cans (Modmic style) and adapting TRRS to TRS/TS microphone.

In fact, I'm not even a fan of combining headphone L+R channel ground returns before the very end of the cable, as that invariably compromises channel separation - so really, even a pure headphone cable ought to be TRS immediately splitting into 4 conductors and terminating in TRRS up top. Sennheiser is doing it right (HD598, HD5x9), while the X2HR with its 3-pin jack headphone side and fairly low impedance drivers (30 ohms nominal) is not ideal. As a rule of thumb, shared ground return resistance should be less than 1% of nominal headphone impedance. Getting <0.3 ohms from a decent-length headphone cable is a bit of a stretch.

I would be looking for something similar to your present SES-TRRS-AB, but 2x TRS. Or make one, since you seem to be about ready to go down that route. Might not be trivial to build as a pure passive box... if I'm not mistaken you'd need a 6PDT (or at least 5PDT) switch. They do exist but would probably have to be ordered from one of the big parts distributors. You could do two separate 3PDT switches, one per jack, but that would make things a bit more cumbersome (unless you can see an application for headphones on one computer and mic on the other). And even those still aren't nearly as common as DPDT switches.
 

zack20cb

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Thanks AnalogSteph, this is helpful. I've considered making my own switchbox...I hadn't considered doing a six-pole switch with independent grounds for each channel, that's a great idea.

Followup questions:

1. Does my current setup risk harming my hardware (or is it just suboptimal in terms of interference)?

2. I'm using a USB-C DAC/ADC dongles on the laptop. As you say, I can eliminate the ground loop by establishing a dedicated ground for the microphone (retire the Boompro and switch to a Modmic, for example...possibly make a 5-conductor or 6-conductor cable, I really don't love the idea of juggling parallel wires at my desk). Having done this, I would still have a shared ground coming out of my DAC, running to my TRRS switchbox, etc. I could make an adapter box that splits this out into six conductors (left, right, mic, and ground for each), to minimize sharing of grounds. Do you think this would make sense, or does it not matter because these grounds would still be bridged at the DAC/ADC's TRRS jack?
 

Harrycol501

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Hey all, looking for a new desktop AMP to drive the Hifiman HE400se. My current setup is the SMSL Sanskrit 10th II DAC and an old but reliable cheap Music Fidelity AMP. I'm happy with the DAC, but looking for a more modern upgrade to the AMP. Looking to get the best possible neutral sound... If it can boost the sub bass of the 400se then great, but not essential.

Open to suggestions up to £150 max. Anyone with experience with the following AMPs with a planar - or even better with the 400se itself - then love to hear your opinion. From reading, a lot of listeners recommend a balanced setup with planars, but for me it's not essential.

Schiit Magni 3
JDS Atom + AMP
Ifi Zen Can
SMSL SH-6
Topping L30
 

staticV3

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@Harrycol501 From an objective standpoint, I'd scratch the Zen Can off the list, replace the Magni 3 with the Magni Heresy, and add the Sabaj A10h.
 

raif71

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Hey all, looking for a new desktop AMP to drive the Hifiman HE400se. My current setup is the SMSL Sanskrit 10th II DAC and an old but reliable cheap Music Fidelity AMP. I'm happy with the DAC, but looking for a more modern upgrade to the AMP. Looking to get the best possible neutral sound... If it can boost the sub bass of the 400se then great, but not essential.

Open to suggestions up to £150 max. Anyone with experience with the following AMPs with a planar - or even better with the 400se itself - then love to hear your opinion. From reading, a lot of listeners recommend a balanced setup with planars, but for me it's not essential.

Schiit Magni 3
JDS Atom + AMP
Ifi Zen Can
SMSL SH-6
Topping L30
Cool you have the Zen Can in your list. I have it and it is a pretty powerful amp. :)
 

Harrycol501

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@Harrycol501 From an objective standpoint, I'd scratch the Zen Can off the list, replace the Magni 3 with the Magni Heresy, and add the Sabaj A10h.

Hmmm, surprised I missed the A10h, thought I saw all the SMSL amps. Looks decent, good price. I'll do some research on that one now.

I'd be looking at second hand eBay UK for schiit amps, the Heresy don't turn up often, the Magni 3+ does, normally for £100ish.

The Zen Can was my first choice until I saw the review on here and it's made me hesitant.

Edit: just realised you wrote Sabaj lol. I've had the Sabaj DA3 before which I really liked, so it's a brand I am familiar with. Reviews seem very good.
 
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pk500

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Hey all, looking for a new desktop AMP to drive the Hifiman HE400se. My current setup is the SMSL Sanskrit 10th II DAC and an old but reliable cheap Music Fidelity AMP. I'm happy with the DAC, but looking for a more modern upgrade to the AMP. Looking to get the best possible neutral sound... If it can boost the sub bass of the 400se then great, but not essential.

Open to suggestions up to £150 max. Anyone with experience with the following AMPs with a planar - or even better with the 400se itself - then love to hear your opinion. From reading, a lot of listeners recommend a balanced setup with planars, but for me it's not essential.

Schiit Magni 3
JDS Atom + AMP
Ifi Zen Can
SMSL SH-6
Topping L30
I have used a JDS Atom+ amp and DAC to drive my HE-400se beautifully. Plenty of clean power for that headphone.
 
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