Down into the rabit hole of the Audiophile - DAC and headphone Amp.

[Black Phoenix]

Well, I will ask here since this is a forum of EEs not of people who get fooled easily.

I'm looking for a good DAC and Headphone Amp to run a future headphone I will be buying - Still deciding between the AKG 7xx series (701, 702, 712, Drop 7xx) or a Beyerdynamic DT 1990 Pro. My scenario is I also wanted to be able to power together with the Amp some studio monitors, so the dac should have an exit for studio monitors, being XLR or any other kind of connection to active studio monitors.

From what I saw one of the most used is the Schiit Stack (Modi 3 and Magni 3).
I also see, since I'm in China, a lot from S.M.S.L and their price is also very competitive for the specs they have, but I don't have any experience between any of them.

My question is if any of the users use any kind of DAC and headphone amp, what is the ones they use?

[tszaboo]

I have the SMSL sApII Pro, which is a TPA6120A2 amplifier. Supposed to be the best TI chip to drive headphones. I tried it with a HD600, but I couldnt hear any difference. I think it is 50% your hearing, 40% the headphone, 9% the time of day, 1% the amp/dac for the listening. 

[Black Phoenix]

Are you interested in an Apogee Groove? It works under latest version of all major OSes without third party drivers, though they do offer one rebranded from Thesycon.

I'm asking because I have a spare one, but that's in my home in Shenzhen, and I'm not coming back before 17th.

It's for what I see a Headphone Amp USB powered for all equipments and even work with phones right?

It might be interesting specially for starting up. Since I also don't know when I'm available in Shenzhen. I would keep that in the back of my head, let me read more about it.

[Black Phoenix]

It will work with a phone if your phone can supply 300mA+ or you use a power splitter cable with an external PSU.

It can output quite a high level for an HPA, well into line out level, but don't expect crazy high level. It will feed an external integrated power amp or HPA well. Just don't expect it to feed those +7dbV XLR studio grade gears.

I would not expect to do that to Studio Monitors.

What I see normally people using that can use as an DAC is USB Audio Interfaces in the likes as Focusrite Scarlett 2I4:



It can power a Headphone and output to Studio Monitors, but is basically an USB Sound Card, not an Amp. What I was looking is something like the RME ADI-2-DAC:



But it costs an arm and a leg plus a kidney (I'm not saying is not really deserved the price, but I would like to see the BOM of it compared with the sale price) as typical of audiophile material.

[magic]

TPA6120A2 amplifier. Supposed to be the best TI chip to drive headphones.

This chip could die already. With 10Ω output resistor required for stability it might be fine for the big AKGs and Beyers, but not so much for driving low impedance, particularly multi-way IEMs with passive crossovers.

It's a rebranded DSL line driver and little consideration was made for low frequency THD (thermal effects). One may argue that it makes no practical difference and one would probably be right, but still looks lame on the spec sheet.

If you want TI, they have some high current opamps pretty much designed for HP drive in the OPA16xx series.

[jogri]

I am currently using either a Denon 2808, 1909 (i swapped the DACs of this unit with TI 1602s) or my Asus Xonar Essence sound card to drive my Beyer 1990 Pros, but there isn't any significant difference between them. I couldn't tell which DAC/amp i'm using from hearing alone, as long as you have a high quality input (i personally recommend HDMI, but Toslink is also fine if you just want to connect stereo speakers).

Get yourself a good pair of headphones (because you will definitely hear the difference between a Beyer 770 and 1990 [i have both]), but judging from my (limited) experience with different DACs/amps there isn't any huge difference between good ones.

Why do i use AVRs to power my headphones? 1.Extremely cheap on ebay since no one wants a Full-HD AVR anymore 2.supports a lot of different inputs 3. you can hook up your studio monitors and have the possibility to upgrade to surround sound.

[Pitrsek]

This chip could die already. With 10Ω output resistor required for stability it might be fine for the big AKGs and Beyers, but not so much for driving low impedance, particularly multi-way IEMs with passive crossovers.

I'm pretty sure it does not need 10Ω output resistor. It most probably needs a restive output impedance around frequency where the feedback loop closes. Suitable chip bead or ferrite on output cable would do the job. Without messing the audio band.

[magic]

I'm pretty sure it does not need 10Ω output resistor. It most probably needs a restive output impedance around frequency where the feedback loop closes. Suitable chip bead or ferrite on output cable would do the job. Without messing the audio band.

It's not that simple because ferrites have nonlinear magnetic characteristics and they can mess up the audio band if there is current drawn by the load. I think some people claimed getting it under control by picking "good" inductors, presumably with highly overrated saturation current spec, but you can't just whack any random choke in there.

Speaker amps almost invariably use bulky air core inductors and many implementations of the TI chip end up settling on resistors, like the popular Xonar STX sound cards.

[tszaboo]

TPA6120A2 amplifier. Supposed to be the best TI chip to drive headphones.

This chip could die already. With 10Ω output resistor required for stability it might be fine for the big AKGs and Beyers, but not so much for driving low impedance, particularly multi-way IEMs with passive crossovers.

It's a rebranded DSL line driver and little consideration was made for low frequency THD (thermal effects). One may argue that it makes no practical difference and one would probably be right, but still looks lame on the spec sheet.

If you want TI, they have some high current opamps pretty much designed for HP drive in the OPA16xx series.

The HD600 is a 300 Ohm headphone, so I dont think that 10Ohm matters. Honestly, I bought the unit, just to see if I can hear the difference... and nothing. My theory is that 95% of the music is routed through dozens of NE5532s, bunch of DSPs from 1980, and then the mixing engineer does something with it. So it is louder, and the samsung boombox can rock the average Joe. And it doesnt matter anymore what kind of DAC or AMP you have.

[Ed.Kloonk]

It can power a Headphone and output to Studio Monitors, but is basically an USB Sound Card, not an Amp. What I was looking is something like the RME ADI-2-DAC:



But it costs an arm and a leg plus a kidney (I'm not saying is not really deserved the price, but I would like to see the BOM of it compared with the sale price) as typical of audiophile material.

Works with Linux.

[ve7xen]

I mean because you asked, even though it's not really relevant to what you're looking for... I'm currently nearing what might (pfft who am I kidding) be the end of a multi-year side project to build a small integrated USB powered UAC2 DAC+HPA with reasonably low jitter clocks. The UAC2 part has been fairly non-trivial, no off-the-shelf solutions are available, and I don't have the low-level USB chops (or the time) to implement it myself from scratch. XMOS is the only vendor I'm aware of with reference code available, but their chips are 'weird', expensive, and have thermal pads that *must* be soldered. After quite a lot of difficulty soldering the package properly with an iron, and a few weeks futzing around with the development environment and porting the reference code to my hardware, I have got an XMOS-based solution up and running quite well with dedicated 44.1K and 48K clocks, supporting 24b/192KHz. It mates with a CS4398 DAC, using OPA1656 for filtering and as a headphone amp stage, running at +/-9V. It all fits in a Hammond 1455C801 case. I think it probably blows the USB 500mA budget a bit but seems to work fine. It does indeed get hot, and I don't know enough about the XMOS microcontroller to know if a ton of stuff could be turned off to save some power, it's a pretty power hungry micro. Sounds great, though . I'm mostly driving relatively low impedance DT770 Pro 80's with it.

Future direction for this is to try and design a slightly less densely packed 'desktop' DAC with less DC-DC, a separate 2-channel DAC for speaker output, and an ADC input.

The O2 Headphone Amp is a good design to investigate if you're considering going down the DIY road yourself. Very objective design, design decisions are well discussed and justified. Same guy released a UAC1 DAC back in 2012, but it relied on a proprietary USB interface chip. It's too bad the guy disappeared, because his blog had some great measurements / reviews of popular 'low end audiophile' equipment.

[Zucca]

https://www.diyaudio.com/

[Ed.Kloonk]

https://www.diyaudio.com/

That's a deep rabbit hole that I've yet to be able to jump out.

I got a migraine by just skimming the first dozen or so topics.

[Zucca]

That's a deep rabbit hole that I've yet to be able to jump out.

So no more diyaudio for you? really?

[Pitrsek]

It's not that simple because ferrites have nonlinear magnetic characteristics and they can mess up the audio band if there is current drawn by the load. I think some people claimed getting it under control by picking "good" inductors, presumably with highly overrated saturation current spec, but you can't just whack any random choke in there.

Suitable chip-bead != any random choke.  With a bit of patience, you can find a chip bead that is pretty much restive through the audio band. 
I just wanted to point out that the datasheet 10R is not the only solution.
EDIT: It might be good idea to put resistor parallel to the chip-bead, to better control HF impedance