Review and Measurements of Okto DAC8 8Ch DAC & Amp

[dean70]

The audio manufacturers mostly do not develop t NHheir own ASIO driver, but they licence it from a German company called Thesycon. We are deciding on the following steps to take regarding a Windows ASIO driver. But we have tested ASIO4ALL as an output of JRiver, combined with JRiver's "virtual soundcard" WDM driver and its DSP studio and this combination works well. We didn't test with dePhonica though.


Exactly. But it is also good to have some DNR headroom for DSP purposes, since to make a "+20dB" correction in bass region, actually the rest of the audio band needs to be attenuated by that amount to avoid clipping, so except for the corrected region, 20dB of DNR is lost (regardless of whether an analog or a digital attenuation is applied later on).


A single-tone THD measurement is a useful indicator of a nonlinearity of a transfer function, but the harmonic distortion components themselves (as per their name) are in harmony with the original tone, being at whole-number multiple of its frequency (according to the music theory a whole number of octaves higher), so although they do produce coloration, they are not offensive. When multiple tones are introduced, their interaction on such a nonlinearity creates tones at differences and sums of the original frequencies (intermodulation) - not in harmony with the originals. That is addressed by the 32-tone test in ASR reviews, which is close to a real music data.

A synthetic test to determine distortion audibility should include a base tone and a non-integral "offender" tone (maybe a swept one).


No, 192kHz PCM and DSD128 are the maximum data rates for the DAC8 PRO regardless the number of active channels. The limitation is due to XMOS firmware for 16 channels in total (8 in, 8 out), but honestly, we don't see much reason to go further. Performance of DAC chips gets worse at high sample rates (that applies to both ESS as well as AKM ones) so you gain bandwidth in ultrasonic (inaudible) region in expense of making things worse within the audible region.

Pavel, Okto Research

If the DAC8 is used as the basis of a home theatre system the mixing capabilities are not required. Could a menu option be considered to disable and free up bandwidth to enable higher sample rates? The only other product that supports 8 channels of DSD256/PCM 384k is the Exasound E38 at 4 times the price (and no xlr out). This would make the DAC8 unique for HT or active crossover computer based audio systems.

 

[Kal Rubinson]

The only other product that supports 8 channels of DSD256/PCM 384k is the Exasound E38 at 4 times the price (and no xlr out).

Available with miniXLR output.

 

[th0m]

The easiest way is just to simply connect the required number of channels together externally (DAC8 PRO outputs don't mind that). Each doubling of the number of summed channels will cause sqrt(2)-times decrease in RMS noise value due to its uncorrelated nature and normal distribution.

Excuse my ignorance, but how would you go about doing this? Physically combining the 8 channels into a stereo setup I mean. I would be connecting it directly to the XLR inputs of a stereo power amp (Electrocompaniet AW120 DMB) if that's relevant.

 

[SpyB]

Excuse my ignorance, but how would you go about doing this? Physically combining the 8 channels into a stereo setup I mean. I would be connecting it directly to the XLR inputs of a stereo power amp (Electrocompaniet AW120 DMB) if that's relevant.

I quote Amir :
https://www.audiosciencereview.com/...nts-of-okto-dac8-8ch-dac-amp.7064/post-162581

"On USB, the device exposes 8 channels of audio. By default audio apps send their stereo signals to channels 1 and 2. So that is how the routing works (i.e in software, not hardware)."

Amir
Founder, Audio Science Review

 

[th0m]

I quote Amir :
https://www.audiosciencereview.com/...nts-of-okto-dac8-8ch-dac-amp.7064/post-162581

"On USB, the device exposes 8 channels of audio. By default audio apps send their stereo signals to channels 1 and 2. So that is how the routing works (i.e in software, not hardware)."

Amir
Founder, Audio Science Review

Yeah, I understand that. The reason I'm asking is because I'm curious about the possibility of getting even lower RMS noise levels and higher dynamic range etc if you summon the channels externally like Pavel said. I'm thinking you would need to use for example a pair of 4-XLR-to-1-XLR cables of some sort.

 

[Absolute]

This device is seriously intriguing, but I have a practical question;

Because I'm stupid I send all sources (pc, ps4, eh...tv signals) through my TV, which can only send out sound through either optical or HDMI ARC. Let's say I want an active three-way system and want to still use my TV as center of attention even when it comes to sound, how do I best do that?

 

[Kal Rubinson]

This device is seriously intriguing, but I have a practical question;
Because I'm stupid I send all sources (pc, ps4, eh...tv signals) through my TV, which can only send out sound through either optical or HDMI ARC. Let's say I want an active three-way system and want to still use my TV as center of attention even when it comes to sound, how do I best do that?

You will need more equipment to implement the crossover. Some thing like a computer or a preamp processor.

 

[Absolute]

If I'd like to keep things as simple as possible, what would be a recommended solution? A pc can, and therefore will, make things iffy from time to time, so I'd prefer a simple box. Could I use any of the digital MiniDsp boxes? Or would I need a proper processor?

 

[Kal Rubinson]

If I'd like to keep things as simple as possible, what would be a recommended solution? A pc can, and therefore will, make things iffy from time to time, so I'd prefer a simple box. Could I use any of the digital MiniDsp boxes? Or would I need a proper processor?

You are trying to do something complex and sophisticated on the cheap and with the minimum possible toolkit. This seems more iffy to me. I am not sure that there is a single miniDSP box that will do this.

 

[Absolute]

Well, yes. If we can't use science to make complicated things cheap and simple, what's the point?
I need enough to make things work without compromising on both quality and simplicity, but I don't exactly know what that would be.

I have a pc, I have Audiolense XO and I do have a Minidsp 4x10HD, but I figure this minidsp will compromise performance due to lower end dac-quality. I don't know/understand how to make a pc with Audiolense work when I need my system to work flawlessly and simple with the TV.
I was thinking that a clever digital box that can make use of either optical or HDMI and pass this on to Okto Dac8 would be the simplest and best way, but I appreciate any advice or suggestions.

 

[Kal Rubinson]

Wasn't there some proposed version of the OKTO that was supposed to do this?

 

[g29]

Oct 24, 2019 Has anyone in North America received their production DAC8 PRO yet ? If so, please provide feedback.

Bump, Has anyone in North America received their production DAC8 PRO yet ? If so, please provide feedback.

TIA

 

[bigjacko]

Yeah, I understand that. The reason I'm asking is because I'm curious about the possibility of getting even lower RMS noise levels and higher dynamic range etc if you summon the channels externally like Pavel said. I'm thinking you would need to use for example a pair of 4-XLR-to-1-XLR cables of some sort.

Can you talk a bit about how it works and the benefit of combining 4 xlr into 1? Or maybe can you show me article or website that I can read?

 

[g29]

Can you talk a bit about how it works and the benefit of combining 4 xlr into 1? Or maybe can you show me article or website that I can read?

If you compare the stats (SINAD and DNR) between the PRO and STEREO versions on the OKTO Research webpage, it should give you an idea of the benefit.

 

[wineds]

Bump, Has anyone in North America received their production DAC8 PRO yet ? If so, please provide feedback.

TIA

Yes I wonder when they will start shipping the dac08 pro?

 

[th0m]

Can you talk a bit about how it works and the benefit of combining 4 xlr into 1? Or maybe can you show me article or website that I can read?

Pavel touches on it a bit in this post: https://www.audiosciencereview.com/...nts-of-okto-dac8-8ch-dac-amp.7064/post-215170

 

[bigjacko]

So is the stereo version the same performance as 8 channel version that combine 4 xlr into 1? Does simply connect 4 into 1 means solder 4 xlr wires into 1?

 

[th0m]

So is the stereo version the same performance as 8 channel version that combine 4 xlr into 1? Does simply connect 4 into 1 means solder 4 xlr wires into 1?

As I understand it, yes. I spoke to Blue Jeans Cable about making custom cables like this and it wouldn't be a problem. I suppose using three Y-splitter cables (two splitter cables going into one splitter cable) per channel would also work.

 

[1234VICE]

I was thinking that a clever digital box that can make use of either optical or HDMI and pass this on to Okto Dac8 would be the simplest and best way, but I appreciate any advice or suggestions.

The DAC8 can record spdif via aes/ebu. You could use a spdif optical to coax converter and a coax to aes xlr cable to connect the digital out of the tv to the recording input of the dac8. You could also use a spdif optical to aes converter, but those are harder to come by.

Next you can connect a computer to the dac8 via usb. In windows set the okto dac to "listen to device". You have now essentially added an optical input to your pc. The pc can then be used as dsp and to output 8Ch digital audio back to the okto dac8.

There are some downsides to this:
-Only 2Ch input via optical
-The sample rate and bit depth need to be the same for recording and playback for the dac8 (you will be limited by the output format of your tv)
-Potential latency issues

There are also soundcards with optical input that you could buy, in order not to use the dac8 for recording. Such as the ESI U24 XL. You will probably need to use an asio driver in order to keep recording latency down though.

 

[Absolute]

The DAC8 can record spdif via aes/ebu. You could use a spdif optical to coax converter and a coax to aes xlr cable to connect the digital out of the tv to the recording input of the dac8. You could also use a spdif optical to aes converter, but those are harder to come by.

Next you can connect a computer to the dac8 via usb. In windows set the okto dac to "listen to device". You have now essentially added an optical input to your pc. The pc can then be used as dsp and to output 8Ch digital audio back to the okto dac8.

There are some downsides to this:
-Only 2Ch input via optical
-The sample rate and bit depth need to be the same for recording and playback for the dac8 (you will be limited by the output format of your tv)
-Potential latency issues

There are also soundcards with optical input that you could buy, in order not to use the dac8 for recording. Such as the ESI U24 XL. You will probably need to use an asio driver in order to keep recording latency down though.

Thank you for providing an excellent suggestion on how to solve a problem which, to me at least, is complicated and not straight-forward! I suppose the limitation of 2Ch input isn't a problem for me in a stereo + multi-sub set-up, so this solution can work.