Need help with ASIO drivers

I'm trying to add a couple of external audio devices to my system (SPS-25 and SPS-66). I downloaded and installed the latest drivers. Both devices appear in the audio-devices section in the preferences menu but they are greyed out and I cannot select them. I have the latest version of X-1 Producer; I am running Windows 7 Ultimate; I am currently using the ASIO drivers for my existing Layla24 and Layla3G internal sound cards (they both work fine). Any ideas?

Unless the driver supports using 2 devices (obviously from the same manufacturer) ASIO can only address 1 device at a time.

In the case of the LAYLA cards apparently the driver can see them both because it's written that way. Unless you disable the Layla driver you won't be able to see the SPS25 and/or 66 cards. Whether their driver allows them both to be recognised together is another matter which you'll only know by reading any release material you have or trying it. One thing is for sure and that is that you won't be able to have the Layla and the SPS cards run together as you've already discovered. At least not using ASIO drivers.

IF you change to WDM drivers or WASAPI or WAVERT you may be able to see all the cards. The problem is that each digital audio device has its own clock which determines how accurate each sample is recorded/played and unless you have a way to synchronize all your devices you won't get accurate playback and recording.

Some devices have drivers that provide for software synchronising while others need a dedicated hardware connection through a Clock/synch, SP-DIF I/O.

You won't be able to over come the ASIO limitation between devices from different manufacturers by connecting clock I/O between devices.

Some people have had moderate success using a program called ASIO4ALL. Some software will only work with ASIO drivers. In years gone by not all hardware had ASIO drivers (today most onboard sound devices only have WDM or MME drivers). ASIO4ALL wraps the WDM driver making the operating system think that it is looking at an ASIO driver.
It will allow you to Concatenate devices. No guaranteed success and even though you may be able to see multiple hardware devices in a host like SONAR, you still don't have the synchronization issue solved which will invariably lead to problems. When you think of synchronization it is not just synchronizing the clocks between devices but also the quality of each sample that's recorded and playback.

At the most basic level a device needs to accurately record or playback 44,100 samples every second at a variety of bitdepths or resolutions. It's ability to do this sampling is determined by its own internal hardware clock. Think of the margin for error when you have 2 or more devices playing simultaneously using their own clocks with no way for each device to report its timing to the other.

The typical way to get more inputs and outputs is to have a device that has ADAT connections providing the additional I/O and clock ports.

Of course some hardware can use multiple devices. A general rule is though that they all see the same driver and that there is some proprietary software written to let you manipulate all your I/O. One of the devies acts as the clock for all the devices. You can connect multiple FF800's on the same FireWire bus. many manufacturers make devices that can be connected in multiples using ASIO drivers but in effect it's still addressing a single multi I/O device through the one driver.

Infact the ASIO limitation is to one driver not one device.
It's not a SONAR issue rather a driver issue and a limitation of the ASIO specification.