@ejspain2020 If it sounds better, it would not be because of the clock in the Iris, which is worse than the Venus’ clock from a technical standpoint. If you are hearing benefits with the Iris without slaving it to the Venus’ clock (which would involve using the 2 clock out BNC ports on the Venus connected by 2 BNC cables to the 2 respective clock in BNC ports on the Iris), then it is because you are experiencing the other benefits of the DDC other than better reclocking (ie. galvanic isolation, etc. as explained by @vthokie83 previously). This, in turn, likely means that the USB signal coming out of whatever streamer you’re using into the Iris is likely poorly implemented. The only input on the Venus that would use the Venus’ very good OCXO clock (which is arguably the biggest upgrade from the Pontus to the Venus 15th and one of the biggest reasons as to why you would have paid extra over the Pontus for the Venus) is the Venus’ USB input because it is the only asynchronous input. Every other input uses the clock of the upstream device it is coming from. However, it could also be argued that you are not really hearing an improvement because 1) the isolation in the Iris is not really better than the isolation offered by the Venus’ USB input, and 2) I2S input in and of itself is not better than the USB input on Denafrips’ Venus and Terminator, as Denafrips themselves recommend using the USB input for these higher model DACs (because they say the isolation and clock is much better in these DAC models than any of their DDCs). Honestly, there is no reason to use any of the DDCs by Denafrips or Musician with the Venus from a purely SONIC perspective if you are not going to slave it to your Venus (you would be downgrading your clock - or at least not upgrading the clock in any meaningful way if you don’t buy what Denafrips claims, using a synchronous I2S signal that is more prone to interference with HDMI or RJ45 cable runs longer than 1-1.5ish meters compared to USB cable runs, etc.). If you need more inputs, then the Hermes and Gaia would offer that (though that is a good chunk of change to spend for input switching when there are some cheaper DDCs that allow you to do that, especially if you are not slaving your DDC to the Venus anyway). Even if the OCXO clocks in the two higher end Denafrips DDC models are exactly the same as the single OCXO clock that is in the Venus (not sure if this is the case or not, but like @vthokie83 stated with USB, clock implementation is just as important as the clock itself), I think it would still be beneficial to slave them to the Venus DAC’s clock because then both devices would be in sync using the same clock. If you want to see if you should keep the Iris or not, you should 1) use your new streamer if you are going to upgrade your streamer, and 2) slave the Iris to the Venus’ clock with 2 quality BNC interconnects (I think it should be 50 ohm BNC cables for this connection, but I would double check). Then listen and see if you hear a difference between your streamer’s USB out going directly into the Venus’ USB in VERSUS your streamer’s USB out going into the Iris’ USB in and then the Iris’ I2S out (HDMI or RJ45) into the Venus’ I2s in.