Hello folks,

I have used my Fireface 400 for over ten years and it is still going strong. I recently picked another Fireface 400 up to daisychain and have run into a strange issue. The software output from Reaper is being blocked somehow whenever the second Fireface unit is connected. If I hit play in Reaper with the masterbus routed to the first FF400, I see the meters jump for a fraction of a second in totalmix and hear a feint click in the headphones but then there is nothing. The meters in Reaper show output but totalmix shows no activity.

If I route Reaper to the second fireface, all works as it should. If I disconnect the second Fireface, the first unit behaves as it should, receiving audio from Reaper. I would have suspected some sort of problem related to me using firewire on a relatively modern PC on Windows 10, but all the inputs from both units work as they should which makes me think there is something else going on.

First unit is master, word clock via BNC to second unit which shows sync. DAW is Reaper, OS is Windows 10. Ive got latest drivers and firmware for the firefaces. I use the Thesycon Fire Wire driver. I've been running the single FF400 with this PC for around 5 years and its been fairly trouble free. I have tried running both Firewire units into the PC on seperate firewire cables and also initially with one connected to the other in case this made any difference.

Many thanks in advance