I’m not an expert mind you, but here’s what I’ve known from in part my own experience, and what I’ve been reading throughout the years …
Being they’re both audio interfaces, and each need to use their own specific drivers, I tend to doubt it. Last I heard you can’t use 2 different types of interfaces simultaneously, as you can’t select more than one ASIO driver at a time within Cubase. This is referring to using multiple ‘drivers’ mind you…whether you can actually use each, for their own different specific functions ‘without’ using both drivers simultaneously - say for example, one as a transport device via midi messages etc, the other as your audio interface - well, maybe then. The point is, you can’t use multiple different drivers.
There’s something called ASIO4All, but personally, I would stay away from that as it’s a crap shoot it’ll work well…and often seen as a last resort or ‘what do I have to lose’ type of thing to try. I use multiple audio interfaces in my home studio set-up, but they’re all from the ‘same’ manufacturer, which all run under the ‘same’ ASIO driver I can run up to FOUR interfaces within a single machine. I personally would not buy an interface that could not allow me to use multiples of it, or use different interface models from the same manufacturer, allowing me to use them under ONE ASIO driver.
If it indeed turns out you cannot use both simultaneously, you have the option of toggling between the two as you need each of their own unique functions, or use them on two separate machines… the use of multiple machines is a whole other story, and something I do. But even still, I use the same manufacturer’s interfaces in each machine for the best compatibility.
I also have a Tascam FW 1082 that I bought from ebay…a music school was selling off several of them. I had planned on using it on a machine of it’s own. I’ve yet to actually use it though. I definitely won’t bother to attempt using it on the same machine along with my other interface…not unless I could use it, playing the simple function of a stand-alone mixing desk inter my other sound card(s) ‘without’ the need to use the Tascam’s drivers obviously.
That’s all I’ve got.
PS…Cubase SX5??? Do you mean Cubase SX1, SX2 or SX3? or Cubase 5?