Headphone Amp Ideas - Minus DAC

[Dimitri]

"Perhaps I'm just under the illusion that a headphone amp that costs more than an O2 is going to sound better than an O2."

Disclaimer: I've not heard the O2, (living under a rock I just came accross is just week-unbelievable, I know)
( other disclaimers available upon request)

The O2 is available for a little more than the cost of parts. I'm tempted to buy one just to listen to it, but I'm afraid I'll keep it instead of getting rid of it
Put a $2499.99 price tag on whatever amp you are listening to now and see if that changes the sound. No, I'm not joking, I'm serious. It's a poor man's placebo effect without having shelled out the cash !

Getting the sound you "expect"/"imagine"/"hope for" from any give pair of headphones depends on the headphones as much as it depends on the amp.
My various pairs of heaphones sound "pretty good" with some amps and not so great with others.

Considering the differences in everyone's hearing, ear canal shapes and sizes and all sorts of other factors, makes picking a pair of heaphones a pretty subjective issue. Just like everything else. Plus although it's "easy" to measure headphones, it's almost impossible to measure what "you hear".

But before I start really rumbling....what don't you like about the way the O2 sounds?

 

[Jorj]

Dmitri, first let me extend you a warm welcome to the forum.....and then respectfully suggest you read more carefully.

I love the sound of the O2. It's a flawless amp, really. It does what it was designed to do with great efficiency. If you have not heard one, go get one. They are that good.

I just want that sound in a balanced version, without a DAC. See the OP.

Of course we understand the psychosomatic response to spending more money. I'm not looking for a $2500 amp. I want a more fully featured $300 amp. Please, take your time, read the thread, and we'll all get along much better!

 

[Superdad]

The Little Labs MONOTOR (http://www.littlelabs.com/peppertes.pdf) is one that I would like to put an ear and an analyzer on. Have read a lot of raves about it. Just wish it was about $200 less.

Really like the channel control knob; being able to mono just left or just right is terrific for doing circuit/parts comparisons during product development. And left minus right is very handy too.

P.S. I know it is ugly as sin, and no BS balanced phone outputs. You NEVER see those in the pro-sound phone amps.

 

[Wombat]

"Perhaps I'm just under the illusion that a headphone amp that costs more than an O2 is going to sound better than an O2."

Disclaimer: I've not heard the O2, (living under a rock I just came accross is just week-unbelievable, I know)
( other disclaimers available upon request)

The O2 is available for a little more than the cost of parts. I'm tempted to buy one just to listen to it, but I'm afraid I'll keep it instead of getting rid of it
Put a $2499.99 price tag on whatever amp you are listening to now and see if that changes the sound. No, I'm not joking, I'm serious. It's a poor man's placebo effect without having shelled out the cash !

Getting the sound you "expect"/"imagine"/"hope for" from any give pair of headphones depends on the headphones as much as it depends on the amp.
My various pairs of heaphones sound "pretty good" with some amps and not so great with others.

Considering the differences in everyone's hearing, ear canal shapes and sizes and all sorts of other factors, makes picking a pair of heaphones a pretty subjective issue. Just like everything else. Plus although it's "easy" to measure headphones, it's almost impossible to measure what "you hear".

But before I start really rumbling....what don't you like about the way the O2 sounds?

I have an O2(and Beyerdynamic 880s) and it is just fine for me but I am getting-on a bit.

 

[svart-hvitt]

THE CHEAPEST AND SIMPLEST...

...is no head amp at all!

Maybe one of your DACs can drive headphone from their (balanced) OUT?

Daniel Weiss suggested I try this a couple of years ago. So it depends on the features of your dac.

 

[Candlesticks]

THE CHEAPEST AND SIMPLEST...

...is no head amp at all!

Maybe one of your DACs can drive headphone from their (balanced) OUT?

Daniel Weiss suggested I try this a couple of years ago. So it depends on the features of your dac.

The output impedance of a DAC is typically quite high whereas good headphone amplifiers have an output impedance of less than 1Ω.

 

[svart-hvitt]

The output impedance of a DAC is typically quite high whereas good headphone amplifiers have an output impedance of less than 1Ω.

Yes. Take a look at the dac’s specifications to see if it works.

Weiss DACs can be used as head amps, so I suggested that these are probably not the only ones capable of driving headphones.

 

[pierre]

In the 400$ range:
- Lehmann audio: https://www.lehmannaudio.com/headphone-amplifiers/home/linear.html#technische-daten
- Lake people: G103 is a classic; http://www.lake-people.de/index.php/headphone-amps-desk-top.html
- Audio gd: http://www.audio-gd.com/Pro/Headphoneamp/NFB1AMP/NFB1AMPEN.htm

P.

 

[SpeedyRodent]

Yes. Take a look at the dac’s specifications to see if it works.

Weiss DACs can be used as head amps, so I suggested that these are probably not the only ones capable of driving headphones.

The output impedance on most Weiss DAC's are in the range of 20+ Ohms unbalanced and 40+ Ohms balanced. This might work on high impedance headphones like the Sennheiser HD 600/650/6XX or Beyer dynamic 250/600 ohm versions. You might run into issues driving low impedance headphones.

Most DAC's are designed to drive loads of several thousands of Ohms. Keeping this in mind, you have to be very cautions of the DAC output specifications and the specific headphone that is being driven by the DAC.

 

[svart-hvitt]

The output impedance on most Weiss DAC's are in the range of 20+ Ohms unbalanced and 40+ Ohms balanced. This might work on high impedance headphones like the Sennheiser HD 600/650/6XX or Beyer dynamic 250/600 ohm versions. You might run into issues driving low impedance headphones.

Most DAC's are designed to drive loads of several thousands of Ohms. Keeping this in mind, you have to be very cautions of the DAC output specifications and the specific headphone that is being driven by the DAC.

Straight from the horse’s (DW) mouth:

«The DAC1-MK2 version has a 0 – Ohm output impedance and up to 17V output level. The output level is adjustable with the trim potentiometers on the faceplate. The range goes way down to no output at all. So this unit can drive any headphone basically. The output power can be several Watts of class A performance.

The DAC1-MK3 has about < 100 Ohm output impedance and the level is adjustable between 0.5V and 17V in 1 dB steps. So this unit can also drive most headphones».

This is a pro grade DAC. Maybe most cheap DACs are not as elaborate and thought-through?

 

[Jorj]

Thanks all for the suggestions! There were a few in there that I had not seen yet.

A bit of searching has netted me a fairly-new Audio-gd NFB28 (2015 rev) with all the custom options. It has the input switching I was looking for, flexible connections, can be run either single-ended or balanced, has a level display, enough power to run small speakers. Picking it up tomorrow.

It has an on-board DAC, which I could have done without, but for the money, I'm not complaining. I may even use it for A\B testing against other DACs. From what I read, this is a quality item, substantially overbuilt, a novel volume control architecture, well documented measurements and good customer service. Seems a solid place to plunk a few Benjamins, and should be a nice foil for playing with gear and seeing if my ears are as good as I like to think they are. (hint: they're not)

Once that Topping D10 arrives, it'll be fun to see if I can hear the diff between an ES9018 (NFB28) and the ES9018K2M (Topping D10), and then see if I can find a reasonably built R2R type DAC and try to get some idea of what the hypetrain sees in them.

Oh, I'm sure most of you have seen, but the Topping DX7s is now up on Massdrop for $399. It definitely factored into my decision, but I decided to go with the tank-like build and greater connection flexibilit of the Audio-gd.

 

[amirm]

Congratulations. Where have you seen its measurements?

 

[Jorj]

@amirm There are some measurements available on the page I linked, about 1/2 way down.

I realize these are pretty generic, but if you own one of Kingwa's products and email the request, he will pull you a copy of the tests for that serial number. The NFB line is well tested (I've seen a couple of the test sheets they use), but not as comprehensively as the Master line. Since I've seen a few of others, I know that they would not be super useful for me, as my Chinese is poor (read: nonexistent).

What is missing, however, are the measurements for the version I'm getting, with the upgraded USB stage and gain controls. Too bad you're on the other end of the country, or I'd happily drop the NFB28 by your place for some time on your test bench.

 

[amirm]

What is missing, however, are the measurements for the version I'm getting, with the upgraded USB stage and gain controls. Too bad you're on the other end of the country, or I'd happily drop the NFB28 by your place for some time on your test bench.

USPS has pretty cheap rates for shipping. I have people sending me stuff rom all over US so if you are willing, I can pay for shipping it back.

 

[Jorj]

I may take you up on that...after I've had some quality time with my new toy. Pretty sure I made the right decision, as that DX7s has two ES9038's, but is far less powerful on the amp side of things, and that is what I was primarily after. Still, now that there are 6 buyers on MD, the price is $379. Not shabby.

 

[Nathan Raymond]

I'm in a somewhat similar boat to the original poster, with a few differences. My backstory: I recently bought a Onkyo DP-S1 Rubato, which has a 2.5mm TRRS jack for a fully balanced output, and out of curiosity bought a Fiio F5 earphone which came with a balanced cable, and a balanced cable for my Hifiman HE-400i and Onkyo ES-CTI300. I was especially impressed with how the HE-400i sounds, and was also impressed with the Onkyo ES-CTI300 balanced (I haven't spent much time with the Fiio F5 yet). At one of my desk listening stations I have an SMSL SD-793II (TI DIR9001, PCM1793, OPA2134). I have very little interest in swapping headphone cables to go from balanced to unbalanced when switching between my Onkyo DAP and the SMSL DAC/amp. I did buy a Fiio 2.5mm TRRS to 3.5mm TRS adapter, so I can make my balanced cables unbalanced easily (a must with MMCX connectors especially).

It's not too hard to find some nice DACs at good prices, but a balanced headphone amp? Wow it's like a desert out there. I found this analysis of the SMSL SAP-9, and someone please correct me, but it doesn't look good:

http://reference-audio-analyzer.pro/en/report/amp/smsl-sap-9-bal.php
http://reference-audio-analyzer.pro/en/report/amp/smsl-sap-9-bal.php
The only nice thing is that it has a 2.5mm TRRS balanced headphone jack, something which is uncommon (though I could adapt 4-pin XLR to 2.5mm TRRS). Not worth sacrificing audio quality for a very minor convenience. SMSL M9 DAC/Amp also has a 2.5mm TRRS jack, but the only review I've found is in French and is short on hard data:

https://www.qobuz.com/FR-fr/info/Hi-Fi/Bancs-d-essai/S-M-S-L-M9179036

Topping DX7s is interesting at the Massdrop price, but I am concerned about it's ability to handle highly efficient headphones (I have some which are low Ohms...) I suppose I could buy/build a passive headphone attenuator for use with those, along these lines:

https://diyaudioheaven.wordpress.com/headphones/headphone-attenuation-adapter/

Maybe even build it into a custom XLR to 2.5mm TRRS adapter. Alternatively, I could wait for the Monolith Desktop Headphone Amplifier and DAC to come out and see if we get some good reviews on it, looks like it could potentially be promising:

https://www.monoprice.com/product?p_id=24459

But maybe my premise is wrong? Maybe balanced itself isn't inherently a lot better, but rather the balanced output on the Onkyo DP-S1 DAP is better than it's unbalanced output and better than the unbalanced output of the SMSL SD-793II? And maybe if I just use a better unbalanced desktop amp than the SMSL SD-793II would leave me better off? Haven't found a really good review of the SD-793II yet, here are the specs:

http://www.smsl-audio.com/productshow.asp?id=119

What do folks think?

 

[amirm]

But maybe my premise is wrong? Maybe balanced itself isn't inherently a lot better,

First welcome to the forum!

That is a question I like to investigate with measurements one day. I know Benchmark is against balanced headphone output.

 

[Jorj]

Welcome, Nathan!

You're right, it's tough to find 'amp only' gear. DACs are so cheap to build well that most companies just tack them on in a chassis that is mostly filled with analog devices. I finally gave up and got a hybrid. It's so bad, Emotiva sells the DC-1, which is advertised as a standalone reference DAC. If you read the specs, they grudgingly admit they crammed an amp into the box. Not that the amp is bad, I bet it is fantastic, but you see the mentality. I guess DACs are sexy right now, and amps less so.

I was not able to find much data out there to 'balance' out the hype on balanced vs SE. I wanted an amp that sounded great either way, and for my budget, a used Audio-gd was one of the few that could do what I wanted. I'm personally very skeptical about balanced HP components, but hey, for a few bucks more, I'll play with them and see if I can detect a difference. Measurements don't seem to show that there is any reason to go balanced. Since it is fiddly, expensive and controversial, audiophiles just eat it up, gush about it and generally irritate music lovers by obsessing about it.

I have a great compact solid-state SE DAC\AMP, and just picked up a massive, complicated balanced unit to help keep my desk warm. I'm going to enjoy seeing which I like better.

 

[DonH56]

I do not know if balanced is better on a specific product.

There are several ways to implement balanced, some better than others.

Theoretically balanced (fully differential) circuits offer better SNR than single-ended (SE) circuits and provide shielding and common-mode noise rejection SE circuits do not. Balanced also allows you to "float" the shield ground at one end to break ground loops, since it is not signal ground, perhaps the biggest benefit to consumers.

FWIWFM - Don

 

[Nathan Raymond]

First welcome to the forum!

That is a question I like to investigate with measurements one day. I know Benchmark is against balanced headphone output.

Thanks for the welcome! This looks like a great forum from everything I've read so far - thanks for creating it!

I searched high and low for any critical reviews with good data on balanced vs. unbalanced headphone amps and couldn't find anything on the internet, just lots of opinions or dressed up opinions. I don't doubt that balanced headphone amps can be better if designed well, but what I'm interested in is how much better? Better measured how, and will those measured improvements translate into perceptible improvements? Such a review might be complicated because I imagine some headphones would demonstrate a more noticeable improvement to balanced than others. Unfortunately when I do see it compared/talked about, we get things like this:

https://www.headfonia.com/review-fiio-f5-going-balanced/2/

"Using the balanced cable completely transforms the Fiio F5. You get improved detail from bass to treble making everything sound a lot richer and more energetic. The bass, mids and treble are also more balanced and now have the same amount of body. Besides the extra detail the Fiio F5’s depth and layering especially improve by using the balanced cable. All in all using the balanced cable really makes the Fiio F5 perform on a different, way above its price point, level. In SE mode it’s just another OK sounding IEM but in balanced mode you get this soft, musical, rich and natural sounding IEM. I especially like the softer and natural voices in the balanced setup as the SE config made them clean but too forward and unnatural sounding."

Or this:

https://benchmarkmedia.com/blogs/application_notes/audio-myth-balanced-headphone-outputs-are-better

"Benchmark does not offer balanced headphone outputs on any of its products. The reason for this is that a voltage-balanced interface serves no useful purpose when driving headphones. The truth is that a conventional single-ended headphone drive is technically superior to a balanced drive. This paper explains why single-ended headphone amplifiers are inherently more transparent than balanced headphone amplifiers..."

So I went through my equipment stack and found my old Musical Fidelity V-CAN (pre-MKII), which is a high power headphone amp (5 Ohm output impedance, 109dB A weighted SNR, 0.25W per channel into 32 ohms). Not that high end from what I understand, here's a shot of the board:

https://images.crutchfieldonline.co...50/products/2011/8/778/g778VCAN-o_inside.jpeg

Hooked it up to the line out from my SMSL SD-793II (which is connected via TOSLINK optical to my Mac Mini which is outputting 24-bit 96Khz), and plugged in the 3.5mm TRS to 2.5mm TRRS balanced adapter so I could easily unplug-replug between the V-CAN unbalanced and the Onkyo Rubato DAP balanced.

The Onkyo Rubato has twin SABRE DACs (ES9018C2M) and amplifiers (ES9601K), laid out symmetrically, served by separate capacitors. I find it very curious that I was able to buy the Onkyo Rubato new for $200 yet it is so hard to find an affordable balanced desktop DAC! Here's a decent test of what the Rubato can do:

http://ohm-image.net/data/audio/rmaa-onkyo-dp-s1-rubato-24-bit

I just did some quick comparisons with my Hifiman HE-400i and Onkyo ES-CTI300 running unbalanced to the Musical Fidelity/SMSL combo vs. balanced to the Onkyo Rubato, and while the Rubato was better, there's a lot of factors going on. Quick comparisons (switching as quickly as I could from balanced to unbalanced with the same headphones on the different output jacks of the Rubato) and while I think there's a difference, it's not night and day (on the 24-bit, 96Khz and up tracks I tested anyway). Could be that am unbalanced DAC/Amp better than the SMSL SD-793II/Musical Fidelity V-CAN could match up to the Onkyo Rubato in balanced mode? Wish I had more data to go on...