Upgrade to SPDIF possible? Looking at using with UAD Apollo x6

  • My Profiler is from about 2014 so doesn't have the option to set SPDIF to slave. At the moment, this works fine with my SPL Crimson and I definitely prefer the sound of SPDIF over the analog output.


    Now I'm looking to upgrade my audio interface and since I already have some UAD DSP on PCIe, I'm looking at their product range. The Apollo x6 is the only one with separate SPDIF on RCA so I would like to use this with the Kemper, which would keep the option to add extra i/o on the optical ADAT some time in the future.


    It seems that I should be able to use the Kemper as SPDIF master but from what I'm reading about the new Apollo products, I would then be losing the advantage of the new super tight clocks they've designed. So I'm hoping there's a SPDIF board I could swap out or similar.


    Does anyone have any experience around SPDIF here? Has anyone upgraded their Profilers, if this is possible?

  • Not sure about the board swap - seems highly likely that the SPDIF circuit is integrated into the main PCB. That aside for a moment, I wouldn't get too hung up on master clocks. It's common for manufacturers to infer that the clock quality/PLL chip they've used is going to create some sort of leap in sound quality, when the reality is clocking chips need to be reliable and not drift away from a known sample rate and provide steady modulation without jitter. SPDIF embeds clock signal this way, the same as AES. When that embedded clock signal is received it will be regenerated. So, if your clock in your interface would be slaved to an external device (Kemper), but it would still be regenerating its own clock signal as far as I understand it.

    Instead, I would always think about the workflows that your chosen clocking scheme dictates. It's unfortunate that you will need to slave to the Kemper in this case whenever you power it/attach it and want to use it. If you use your interface frequently without it, then you'll have to keep in mind any blats that can occur as the interface re-clocks, reaching your speakers or headphones. Ideally, the interface would lift its output relays when reclocking to avoid this, but I wouldn't know for the Apollo - worth finding out though as it makes much of the issue go away.

    This sort of stuff is going to bug you much more than the perceived sound of one clocking chip vs another.

    Ed / Audio Systems Engineer / Kemper Stage + Fender fan

  • UAD cards are able to run asynchronous SPDIF. You don’t need to do anything but turn this option on in the console.

    Hm what's it called? Don't see anything related on my Apollo Twin MKI.

    Kemper PowerRack |Kemper Stage| Rivera 4x12 V30 cab | Yamaha DXR10 pair | UA Apollo Twin Duo | Adam A7X | Cubase DAW
    Fender Telecaster 62 re-issue chambered mahogany | Kramer! (1988 or so...) | Gibson Les Paul R7 | Fender Stratocaster HBS-1 Classic Relic Custom Shop | LTD EC-1000 Evertune | 1988 Desert Yellow JEM

  • I think that's the sample rate conversion option. It does seem to work better with it on, but only when you have the clock set to internal. I find it sounds better with it off and you set the clock to SPDIF (external). Then the interface is slave to the Kemper's master clock.


    So .. anyone ever swapped their board? I'm still curious...