Okto dac8 stereo DAC Review

[Manuel]

Has anyone compared its sound (I don't understand measurements) with any R2R component of similar price, such as Gustard or Denafrips?

 

[Sal1950]

Has anyone compared its sound (I don't understand measurements) with any R2R component of similar price, such as Gustard or Denafrips?

Probably won't sound any different but it brings a bunch of extra excellent performing functions to the plate for
a not "high end" cost. A win-winner.

 

[dped90]

Probably won't sound any different but it brings a bunch of extra excellent performing functions to the plate for
a not "high end" cost. A win-winner.

Might you have had any experiences with the SMSL D300, or new SMSL vmv d2r DACs?

I ask this because while my budget is far above the prices of these DACs (e.g. https://www.merging.com/products/interfaces/hapi ), my speaker builder Troy Crowe uses the D300 for evaluating driver/horn combinations and/or completed speaker systems.

What might you expect of the Hapi's sound compared to those SMSL DACs?

 

[Sal1950]

Might you have had any experiences with the SMSL D300, or new SMSL vmv d2r DACs?

No sorry. My last stand alone 2ch DAC purchase was a Emotiva DC-1 which I still use for occasional
serious 2ch SQ evaluations over it's excellent headphone amp.
Otherwise today all DAC chores are handled my by Denon X4700H AVR.
They both sound find to me.

 

[dualazmak]

I just received a notice from OKTO...
Okto Research dac8 firmware v1.6 release

Spoiler

​ Dear audio enthusiasts and dac8 owners, We are thrilled to announce the release of the new firmware version v1.6. It is now available for download for both dac8 PRO and Stereo on the respective product pages, or directly via these links: dac8 PRO firmware v1.6 Release Note dac8 Stereo firmware v1.6 Release Note We apologize for the delay in releasing this update. Your patience and understanding mean a lot to us. We've worked diligently to enhance your dac8 experience, particularly by eliminating clicks when switching between PCM, DSD and DoP. To clarify the issue of clicks: while many competing DACs use analog switches to disconnect or ground the outputs during sample rate changes, we deliberately omitted such components to avoid potential sources of non-linearity. The DAC chip in the dac8 operates in synchronous mode for USB input, deriving the feedback clock from the high-precision oscillator on the DAC board. During sample rate or format changes, one master clock oscillator shuts down and the other is enabled, causing brief transitions that have been the source of clicks until now. We have employed meticulous software control to remove them altogether. The v1.6 firmware also brings an important addition: DoP decoding capability for SPDIF, AES/EBU, and TOSLINK inputs, enabling the dac8 to receive signals from SACD players. The v1.6 firmware is compatible with all dac8 Stereo and dac8 PRO units ever manufactured, and you can expect future versions to maintain this compatibility. This is part of our commitment to providing continuous support and improvements for all our products. We have invested countless hours in developing this firmware and have made extensive efforts to eliminate all previously existing bugs. Therefore, we highly recommend installing this version. If you encounter any issues or unexpected behavior, please report them to us at [email protected]. We hope this update further enhances your experience with our product, allowing you to enjoy your favorite music even more. Sincerely yours, Okto Research

 

[hampestampe]

I just received a notice from OKTO...
Okto Research dac8 firmware v1.6 release

Spoiler

​ Dear audio enthusiasts and dac8 owners, We are thrilled to announce the release of the new firmware version v1.6. It is now available for download for both dac8 PRO and Stereo on the respective product pages, or directly via these links: dac8 PRO firmware v1.6 Release Note dac8 Stereo firmware v1.6 Release Note We apologize for the delay in releasing this update. Your patience and understanding mean a lot to us. We've worked diligently to enhance your dac8 experience, particularly by eliminating clicks when switching between PCM, DSD and DoP. To clarify the issue of clicks: while many competing DACs use analog switches to disconnect or ground the outputs during sample rate changes, we deliberately omitted such components to avoid potential sources of non-linearity. The DAC chip in the dac8 operates in synchronous mode for USB input, deriving the feedback clock from the high-precision oscillator on the DAC board. During sample rate or format changes, one master clock oscillator shuts down and the other is enabled, causing brief transitions that have been the source of clicks until now. We have employed meticulous software control to remove them altogether. The v1.6 firmware also brings an important addition: DoP decoding capability for SPDIF, AES/EBU, and TOSLINK inputs, enabling the dac8 to receive signals from SACD players. The v1.6 firmware is compatible with all dac8 Stereo and dac8 PRO units ever manufactured, and you can expect future versions to maintain this compatibility. This is part of our commitment to providing continuous support and improvements for all our products. We have invested countless hours in developing this firmware and have made extensive efforts to eliminate all previously existing bugs. Therefore, we highly recommend installing this version. If you encounter any issues or unexpected behavior, please report them to us at [email protected]. We hope this update further enhances your experience with our product, allowing you to enjoy your favorite music even more. Sincerely yours, Okto Research

Just performed the update. This time it was easy, just followed the guide provided by Okto.

 

[hampestampe]

I've listened for a while now and switched between different sampling rates. I can confirm Okto have succedes to remove the "noise pops" when switching between them. So seems like they officialy just left the prototype stadium, and now got a fully functional dac on the market.

 

[Kaakatus]

I also updated my unit without any issues. Pops are definitely gone. One minor oddity is the text on Opt1 when there's no signal: "No AES Connection". For example, USB-input says "No connection" when there is no signal.

 

[Peterbean]

This is a review and detailed measurements of the Okto dac8 stereo DAC. It was kindly sent to me by the company for review. It costs €1 089 from the company ($1,240 as of this writing). The version I have has the optional Raspberry Pi 4 module for streaming which costs an extra $89.

Last I tested a dac from Okto, it was their prototype 8-channel DAC. It set a new record in our measurements at the time, getting the highest "SINAD" score possible. While I loved many things about the hardware design, the case needed a new color and thicker sheet metal. Happy to report both of those have been managed producing a very professional and nice looking DAC:

View attachment 73312

As with the last model, the interface is a joy to use with large, bright text that changes lightning fast. An apple remote is provided for control which I used to good effect to navigate the menu system.

The back panel is quite unusual for a DAC:

View attachment 73313

For starters there are dual set of XLRs so that you can use them to connect to two sets of devices (active speakers and a pre-amp). We have two pairs of coax and toslink instead of usual one.

Streaming is provided by Raspberry Pi and while it is physically integrated into the unit, requires that you use the jumper to wire up the dac to its USB output. Fortunately you have another USB input so you don't have to take this in and out.

My unit came with a copy of Volumio software on the SD card which let me stream to it using Airplay. Sadly Airplay only supports 16 bits/44.1 kHz so severely impacted the performance. You can of course change that to another streamer software (e.g. DietPi) or install the Roon endpoint to get full 24-bit streaming at various sample rates.

So I would say the streaming functionality is less than perfectly integrated but as much as they could given the platform restrictions.

DAC Audio Measurements
Competition has gotten quite stiff since I tested the original okto DAC8. Can the new version unseat all the others considering that we are almost at the limit of what my analyzer can measure? Let's find out:

View attachment 73315

Darn it, it did it!

View attachment 73316

View attachment 73317

Yes, the output voltage is a tad high (4.2 vs 4.0) volts which probably helps a bit here. I dialed it down 0.5 dB and it essentially held its performance.

Note that actual performance is better than this as we are including the noise on the input of my analyzer in what the DAC is producing, hence my comment that there is not much more room left to get higher scores.

Speaking of noise, here is the dynamic range:

View attachment 73319

Intermodulation distortion and noise is exceptionally low as one would guess:

View attachment 73320

Multitone as a result is clean as well:
View attachment 73321

And oh, in case you want to use the unit at lower output levels, here it is:
View attachment 73322

So the higher the better but even at just 0.8 volts, you have a SINAD of 110 dB.

Linearity is nailed showing superb accuracy:
View attachment 73323

There are five filters with acronyms I did not try to decipher:

View attachment 73324

Extremely good attenuation for out of band spectrum helps with excellent THD+N versus frequency using 90 kHz bandwidth:

View attachment 73326

Jitter over USB is extremely good:

View attachment 73327

For some reason though, there is some jitter with Coax but not with Toslink or AES/EBU:

View attachment 73328

Headphone Amplifier Tests
I ran a couple of quick tests on the headphone amplifier and was pleased how good its performance is, no doubt helped with such a clean DAC upstream:

View attachment 73329

View attachment 73330

There is good amount of power there but not enough to drive the most difficult headphones.

Edit: added streaming measurements.
Streaming Performance
The unit as supplied was running Volumio. I was pleasantly surprised that the Volumio UI has been enhanced to easily install extensions such as "Roon Bridge" which I used for the following tests:
View attachment 73956

As we see performance is identical to USB which is great. Same is true of jitter test:

View attachment 73957

There is no degradation whatsoever when streaming instead of USB.

Conclusions
okto has done it again: producing state-of-the-art, class-leading, instrument-grade DAC. Not only that, the mechanicals and usability are a good match for it as well. When someone as picky as me can't find any faults, you can tell the job is well done. Very well done.

It is my pleasure to highly recommend the okto dac8 stereo DAC.

------------
As always, questions, comments, recommendations, etc. are welcome.

You would think after seeing such stellar measurements, I would be so happy to not demand more donations. No way. A man would not be a man if more money didn't make him happier. So please donate some money my way using : https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

Thanks for the review
I am setting one up and volume is stuck at -30db
Can somebody please help

 

[poopy]

Thanks for the review
I am setting one up and volume is stuck at -30db
Can somebody please help

Have you checked the volume limiter in the menu?

 

[Peterbean]

Have you checked the volume limiter in the menu?

No what’s that

 

[poopy]

Download the user manual here:

Okto Research

Objective performance

www.oktoresearch.com

And look at page 18.
It looks like the limiter is activated and set to -30dB

 

[Peterbean]

Download the user manual here:

Okto Research

Objective performance

www.oktoresearch.com

And look at page 18.
It looks like the limiter is activated and set to -30dB

Yes! USB 1 was turned down to -50:

Thanks

 

[dped90]

Download the user manual here:

Okto Research

Objective performance

www.oktoresearch.com

And look at page 18.
It looks like the limiter is activated and set to -30dB

Though I suppose most good standalone DACs do, so glad this DAC has a user adjustable limiter. This is especially important to me for movie and TV show playback, as some sound effects can happen unexpectedly and are crazy loud. One movie had this quiet outdoor scene, but suddenly BLAM!! , a huge thunderclap. With my new high efficiency speakers 10 ft away that might othewise cause hearing damage.

 

[nagster]

Latency and output level?

Sorry if this has been covered in this massive thread, I could not find it.

I did some measurements on my Okto 8ch with the latest FW (1.6). I wanted to check latency and adjust level to the rest of the system since I am using other DAC's in parallell.

The Okto was set to Attenuation "0" (volume on full), Pure AES in, all channels level, SRLP filter (the others ring a lot).

I used a BSS DSP unit with one analogue output card to compare and one digital output card feeding the Okto as source. Input signal was a controlled analogue MLS signal via the a BSS analogue input card and the identical signal was fed both the analogue and digital output cards so level and latency should be identical. When measuring I used the Okto analogue out as reference.

Feeding the Okto with digital AES (48kHz / 24 bit) signal on AES input 1&2 (same signal) the output on the Okto analogue out 1&2 was 5.8 db lower than the input signal, when compared the analogue out signal direct from the BSS analogue card. That sounds like a lot?

Anybody else measured the output of the Okto compared to input?

I also tried to measure the latency of the Okto and used the Okto analogue signal as a reference and looked at how much I needed to delay the direct signal to have a timing match between them and came to that the latency in the Okto is 2.1250 ms . That also sound high.

The latency in both the BSS output cards (analogue and digital) is in the femto-range, so it should be neglectable when comparing timing.

Thoughts??

Kind regards
//Rob

This is the impulse response of Okto Research dac8 Stereo. The dac8 PRO may be similar.
I initially intended to measure all sample rates and all filters, but gave up.
By the way, the analog output voltage at 0dBFS input was 4.31V (200kohm load) for both AES and USB.

 

[57gold]

Yo Nagster, for us technically challenged, what do your measurements reveal...in words?

Gracias.

 

[nagster]

Yo Nagster, for us technically challenged, what do your measurements reveal...in words?

Gracias.

The purpose of the measurement is to check the latency and output voltage. There is no purpose to compare linearity or transparency with other devices. (It can be said that less latency is better.)
He mentioned the dac8 Pro, but I thought that even the information from the dac8 stereo would be of some help.

The output voltage of the 0dBFS AES input was 4.31V, which was no different from the USB input.

The USB input has a lot of latency and is not stable, but this is a common shortcoming.
AES/COAX/OPT should be stable. However, for some reason, there was a fluctuation of about 30 microseconds at 44.1kHz, which is not good. Normally, I would investigate thoroughly, but since this was not the purpose of this time, I put it off.
192kHz is stable.

One more thing, I set the digital filter to "SRLP", but the impulse response waveform did not look linear phase to me. If "**LP" stands for linear phase, it could be a bug in the APx software or Okto, or a difference in the filter label. I checked the settings many times but there was no change so I decided to trust the Okto menu display.
This should normally be investigated thoroughly, but as it is possible to estimate differences in latency due to differences in digital filters, I put it off for now.

The measurement results themselves are true, but mentioning the fluctuations and waveform at 44.1 kHz might change the topic, so I only posted the results. I plan to investigate these mysteries again and post a post.

 

[nagster]

I plan to investigate these mysteries again and post a post.

Back to basics, I unplugged the dac8 stereo's power cable and left it.
Here are the impulse response and group delay from the next day. Sorry for the fuss.

 

[nagster]

This is the impulse response for each sample rate of dac8 stereo.
It fluctuated at 44.1k (as well as 88.2k and 176.4k). It was stable at 48k 96k 192k.
For comparison, the same measurements were performed on the RME ADI-2PRO FSRBE.

 

[Feyire]

This is the impulse response for each sample rate of dac8 stereo.
It fluctuated at 44.1k (as well as 88.2k and 176.4k). It was stable at 48k 96k 192k.
For comparison, the same measurements were performed on the RME ADI-2PRO FSRBE.

Thanks for sharing your measurements and findings. By the way, the Okto will accept up to 384 kHz on USB.

Perhaps worth sending an e-mail to Pavel at [email protected] regarding the fluctuating latency and the oddity with the SRLP filter.