PlanetZ forums - scopeusers.com

Mackie 1620i firewire mixer (has ASIO drivers)
Samplitude 11
Scope 4.5

Can Samplitude deal with both the Mackie and Scope at the same time? Can I somehow make the Mackie and Scope communicate with each other?

I have no experience with running more ASIO things at the same time.

No, you'll have to use the Mackie's asio driver and use the scope on VSTIM (XTC) mode with the "jumper trick".
Or use the scope or the Mackie asio drivers and get the remaining card ADAT linked (slaved) to the choosen one.

There are no aggregate devices on PC.