Unavailable devices/ASIO driver

[Grzegorz Moskal]

Why are some devices unselectable in preferences? There are other DAWs on this computer and they are capable of using them all.

Also, where can I select the ASIO driver?

[scook]

Only one ASIO driver may be used at a time.

To change ASIO drivers deselect both input and output then all the driver options will be enabled.

BTW, it may be a good idea to remove the Generic Low Latency Driver. This may be done by renaming the driver or removing the entry from 

HKEY_LOCAL_MACHINE\SOFTWARE\ASIO

As a rule it is a bad idea to have more than one ASIO driver for a given device and generic drivers appear as a second driver for all devices with a manufacturer supplied driver.

[Craig Anderton]

If your devices support WDM/KS, Windows aggregates those devices automatically. Unlike the Mac, you don't need to go into a separate function to aggregate interfaces. Although native Windows audio has a reputation of being slow, I'm able to get 2 ms @88 samples with WDM/KS using a PreSonus 1824c interface, aggregated with the Line 6 Helix USB audio interface. The performance is comparable to ASIO.