Okto Research DAC8 Stereo - Streamer

[Qwin]

This looks fascinating as a Roon Endpoint.
Colour me interested!

Any way Ken a PS Audio comparable i2s output can be introduced to the mix?

No sorry it can't. At least not without some major surgery.
The GPIO socket on the internal Pi is only used for supplying power to the Pi.
Pavel (designer and CEO) at Okto used the asynchronous USB output of the Pi4 for audio.
I asked him and he said it is a very clean signal with no timing issues, on the other hand, the i2s output of the Pi4 is not good and needs re-clocking, it was much more straight forward to use the USB output to achieve good results. The results are spectacular, best measured to date at ASR forum and the subjective sound quality is equally as pleasing.

Note, I found on my PS Audio Stellar GCD that the i2s signal from my CD Transport did not sound as good as its coax SPDIF or AES output. I even bought a fancy (expensive) 300mm long HDMI lead, praised for its audio quality, to try and address this, but it made no difference.

It seems to come down to the quality of the implementation of i2s as to how good the results are. In the case of the Pi, its not done well, Allo do a re-clocking board for the Pi, the Kali, to address this issue, it costs more than than a RPi4B does, think I paid about £70 for one a couple of years back.
Sorry Gaz

[Qwin]

Ooops
I just noticed a typo in my first post.
The lead I modified was a Micro HDMI male to HDMI Female.

[dgolh]

Hi Ken, I'm expecting mine( found 2ndhand) but ufortunately without the Ethernet and the usb interconnect card. I'm waiting for an answer from okto for a possible retrofitting but it will probably take a long time before I can read from them.

Is adding a Rpi4ib an hassle or can a total noob like me handle it? Of course the drill of the back plate might be an issue but I can find somebody to take careof this part of the job.

[ReggieB]

This is top of my DAC wishlist at the moment. There's a very good review of it in Stereophile

[dgolh]

I'm interested in a Soekris 2541 as well, mid-price dacs but very competent.

[Qwin]

Hi Ken, I'm expecting mine( found 2ndhand) but ufortunately without the Ethernet and the usb interconnect card. I'm waiting for an answer from okto for a possible retrofitting but it will probably take a long time before I can read from them.

Is adding a Rpi4ib an hassle or can a total noob like me handle it? Of course the drill of the back plate might be an issue but I can find somebody to take careof this part of the job.

Hi
There is a GPIO socket on the ethernett/usb PCB for the inverted RPi to plug into. Also that you have the SMPS (Black box next to the transformer) this powers the RPi through the GPIO socket. Other than that, cutting the holes is about all you need do. There are a couple of stand offs to locate the RPi.
The main thing is if you have the right power supply, check my picture in the first post, you can see the Black box SMPS above left of the Tranny. If you don't have this on your supply board, you will also need to upgrade to this PSU board.

[dgolh]

Thanks Ken. I can't wait receiving mine !

[Qwin]

You could possibly buy the correct backplate, with all the cut outs from Pavel at Okto.
You will also probably need to change the firmware as well, a friend has the 8 channel version and it definitely uses different firmware.
Have you considered asking Pavel to upgrade it for you?

[dgolh]

Hi Ken

I'm hoping an answer from him on this subject. My fear is that this retrofit could take more or less th esame time than their current lead time. Otherwise, I may take the Soekris way instead.

[Qwin]

Ok
His lead time, at the stated 6-8 weeks, is optimistic at best.
Mine took 15 weeks and my friends 8 channel about 12 weeks.
Mine is a special though, I had the output voltage reduced to 2vrms, to match more normal balanced line level devices, as per my balanced phono stage. I hate huge volume level differences between digital/analogue sources. Mine are now roughly the same, allowing for any mastering differences.
This involved changing resistors that set the gain level, which are SMD and part of the stock PCB's robot pick and place build, so fiddley hand done mods.

With this set up, I don't use the digital volume control, it's set to maximum, which disables it and the display shows 0dB as the output.
I use a separate Pre Amp (Shiit Freya+) for volume. To be honest, once the Okto is fired up, I have the screen auto blank after 5 seconds and it just sits there doing its job. The sound is very neutral using the default filters. My previous DAC, the Topping D90 sounded very slightly cooler, the Okto sounds so natural, you just forget about it being there.
Its a remarkable bit of kit, and for the price a real bargain.