Hello M.C,
thank you for your quick answer.
Sorry but the "Réinitialize" opt doesn't work either.
To be more precise:
When in cubase:
1) If we swap the latency value (higher or lower)
No effect in the cubase visual value for latency.
No effect on the real latency heard
Click on the "Reinitialize" opt from cubase
Then no more sound

2) If we come back to the initial value (the one was setted at the cubase start) for latency
Click on the "Reinitialize" opt from cubase
Then sound come back.

No artifact sound or glitches can be heard at the swap or reinit moments.

3) If we want the changes to take effect we have to close Cubase and resart..
(Not good when you're on session with customers..)

We are a looong time RME products users ( 1hdsp9652, 2 Multiface1, 1 FW800 and now we just switched to the Madiface)
It's the first time we are facing so strange problem with your products.
The madiface is coupled with SSL Madi on 56 Chanels.
Monitoring done via Madiface Analog Output to a SPL.
To restrict the number of channel to 64  we have Mirroring opt so we can see directly the Analogue Input/Output in the cubase connexion panel. So we don't have to use the loopback artifact.

Last information the machine is Win 8.1 Pro 64bits
Thank you

Hello.
The wdm is set to 1 and routed to analog input.
I'll check tomorrow for the cpu load but until last week the config on same machine was 2 multiface1 and ssl via adat..