Battle of Battery Operated Portable Headphone Amps

[Roen]

@amirm

Any interest in measuring and overlaying mains performance on your test graphs?

 

[amirm]

You mean AC measurements???

 

[Johnb]

I think he means on AC power vs battery, THD V Power. Then overlay the two. He mentioned it earlier. And of course, that will only be for the O2, as you confirmed for me that NX3s isn't designed for or good at playing while being charging.

 

[Johnb]

I have to chime in with a shout-out to my current favorite portable amp, actually a wired/wireless DAC/amp: the Radsone EarStudio ES100.

Even if you have ample power/resolution from your 3.5 mm source output, EQ options run surprisingly thin. We’re not talking the power levels of the review units in this thread, but you can clip this on your shirt and go. I regularly hook it up to my HD 650s, when I’m at home. Feels like winning. I can also compensate for China-market-oriented tunings of FiiO IEMs.

Listening to the Live From Here broadcast right now on my iPad>>ES100>>FiiO FA7 on AAC Bluetooth. Not bad.

Yes, wireless. The holy grail of convenience. I've been very curious about the Earstudio. Now, just clip or velcro it to your HD650 headband and make yourself a mini cable. Now that would be fine.

 

[Johnb]

Mikehoope's post reminded me to mention that a very good pairing for either the O2 or NX3s is the Massdrop HD58x. Whereas I run my SMSL Idea at full output with the HD650's, I am able to get the same volume with two or three down from max with the HD58X. Of course, the obvious question is why not just use the Idea then? So convenient to have your amp be part of the headphone cable. I do hate having only around 15 volume steps on the dongle, that is the part that I detest with the Idea. Anyway, just wanted to suggest a decent pairing with the reviewed amps. And IMHO the HD650 is fine as well.

 

[amirm]

I've been very curious about the Earstudio. Now, just clip or velcro it to your HD650 headband and make yourself a mini cable. Now that would be fine.

I have one but been stuck in not having a convenient way to profile its Bluetooth. If you want to know its perf with USB and sample BT codec, I can do that.

 

[HammerSandwich]

I measured signal to noise ratio but the data is junk because both devices severely clip at maximum level which is what is used for determining SNR:
<snip>
I need to devise better test parameters here.

Ref to 1V?

Switching to Hifiman HE-400i to represent low but flat impedance headphone, the O2 was louder but you could hear its distortion easier.

Wait - the O2 wasn't transparent? Or were you able to push it to clipping before your ears gave out?

 

[HammerSandwich]

There is also the issue of running out of gain if the source material is not recorded to max levels.

That's what digital gain is for.

 

[HammerSandwich]

When is an amplifier loud enough? When is gets as loud as you every want, plus a quarter turn of the dial. If you can't blow past your sweet spot, say "Nah, too loud" and dial back, then how will you ever know? How can you ever be happy?

"It will never have enough power until I can spin the wheels at the end of the straightaway in high gear."
- Mark Donohue, on the Porsche 917/30

 

[amirm]

Wait - the O2 wasn't transparent? Or were you able to push it to clipping before your ears gave out?

At max volume, no. You can definitely hear it get distorted. That is why I prefer the JDS Labs Atom over it.

 

[amirm]

That's what digital gain is for.

How do you handle that in a playlist of content???

 

[Johnb]

I have one but been stuck in not having a convenient way to profile its Bluetooth. If you want to know its perf with USB and sample BT codec, I can do that.

As long as everyone knows that the usb is 16-bit, and don't get mixed up about that, it might be OK to have a kind of provisional review. This device really should be measured balanced as well, there might be a great benefit with output power. The great disappointment with every bluetooth I have ever tried was weak output and way too much noise. I'm not sure if the usb input is representative of the level of noise while in wireless mode. They have a boatload of measurements on their site, one could measure on usb and estimate backwards.

The dac / amplification portion could be pretty much sorted out. That is a big portion of the puzzle.

I didn't know you listened to iems until recently. How come you never tried to give it a subjective listen? LDAC is built into newer Android, although I think it depends on the phone chipset being newer. That could be killer as well. Solves the transmitter portion of the puzzle.

Do you think it's worth the effort? You purchased this, right? You have to at least give it a listen.

 

[Headphonaholic]

Thanks for this review Amir! I own an O2 from JDS labs, in fact it was my first headphone amp! I think prior to the Atom it was basically the best entry level amp you could get. I don't view it as being portable even though it has batteries in it. I will also say that in high gain I have had some songs bass notes get demolished by distortion (mine has a higher gain then normal though... don't recall what it is).

If we're talking about truly portable amps my pick is the Creative Sound Blaster E3. I bought one with the goal of having something I can use on my couch or in general around the house. It sounds pretty good and has lots of power. It supports aptx bluetooth which is nice and has 2 headphone outs. I got it for $100 but it looks like it may have been discontinued which is sad

 

[HammerSandwich]

How do you handle that in a playlist of content???

Point taken.

My listening habits are too PC-centric for a mobile-review discussion, I'm afraid.

 

[amirm]

Do you think it's worth the effort? You purchased this, right? You have to at least give it a listen.

The manufacturer sent it to me and they were wonderful in answering my questions early on. So I definitely owe them a review. Will do so as wired USB for now.

 

[mikehoopes]

As long as everyone knows that the usb is 16-bit, and don't get mixed up about that, it might be OK to have a kind of provisional review. This device really should be measured balanced as well, there might be a great benefit with output power. The great disappointment with every bluetooth I have ever tried was weak output and way too much noise. I'm not sure if the usb input is representative of the level of noise while in wireless mode. They have a boatload of measurements on their site, one could measure on usb and estimate backwards.

The dac / amplification portion could be pretty much sorted out. That is a big portion of the puzzle.

I didn't know you listened to iems until recently. How come you never tried to give it a subjective listen? LDAC is built into newer Android, although I think it depends on the phone chipset being newer. That could be killer as well. Solves the transmitter portion of the puzzle.

Do you think it's worth the effort? You purchased this, right? You have to at least give it a listen.

Firmware v1.4.2 from Sept. 2018 added 24-bit USB for macOS sources. I asked Amir about the HD 650 in balanced mode, but he didn’t have a balanced cable for it.

My experience so far with relatively sensitive (115 dB/mW) IEMs has been good - my ears don’t pick up any residual hiss in BT modes.

Their LDAC 660 Kb/s test results (with a 300 Ohm balanced test load) yield > -92-97 dB THD+N.

Their 16-bit unbalanced USB results don’t show anything better than -88 dB.

When using LDAC with my Sony UBP-X800, I have good subjective signal quality at 990 Kb/s.

 

[Johnb]

Hi Mike. Seems like you really like it. I've seen you mention it before, that's why it piqued my interest. I live locally, wonder if we might atg some point meet up and have a mini canfest. What other equipment do you own?

 

[ishmeister]

Looks like the Nx3s has a replaceable opamp. I'm quite tempted by this device to be honest. I would use it with my LG v30 allowing me to untether from my desk with full size cans.

 

[mikehoopes]

Hi Mike. Seems like you really like it. I've seen you mention it before, that's why it piqued my interest. I live locally, wonder if we might atg some point meet up and have a mini canfest. What other equipment do you own?

Hi John - perhaps we can. Alas, I have a relatively small gear collection, decidedly mid-fi. Right now it’s a handful of FiiO IEMs, and a couple of open-back Senns (HD 545, HD 6XX). You can check it out here on head-fi:
https://www.head-fi.org/members/mhoopes.67129/

 

[Johnb]

Looks like the Nx3s has a replaceable opamp. I'm quite tempted by this device to be honest. I would use it with my LG v30 allowing me to untether from my desk with full size cans.

Oh please, don't go down the "op-amp rolling" hole. The default amp design is fabulous. Look at the graphs. The only thing you might do is bork something. The ability to roll op-amps is probably the reason they put a big impedance at the output, as insurance against silly substitutions. That, in turn limited the utility of using this otherwise fine amp with iem's. Pisses me off, they put that socket there.

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