Have any of you heard of this program, if I understand correctly permits multiple hosts to share an ASIO driver?
 
http://odeus-audio.com.au/Odeus/AsioLinkPro
 
 

I have an update on the Focusrite Loopback.  I got hold of Focusrite support and apparently, I am an idiot.  
 
I thought I had done this, but you just need to set the audio drivers to not allow applications to take exclusive hold of the device.  
 
This is a windows setting, not anything on the Focusrite mix panel.  Right click the speaker in the system tray and select "playback devices". Select the Scarlett, properties, advanced, and uncheck "Allow applications to take exclusive control of this device".  There's also the same setting in the record devices.
 
At any rate, after setting things up right, I can send machine out to any of the DAW outputs and use the loopback to run them through Sonar.  I don't have Reason installed currently, but I would expect it to work the same way.
 
So, Loopback with the 8i6 works correctly and multiple applications can use the ASIO driver simultaneously.  

mcdonalk
Have any of you heard of this program, if I understand correctly permits multiple hosts to share an ASIO driver?
 
http://odeus-audio.com.au/Odeus/AsioLinkPro
 
 

Yes I use it, (or rather the earlier version) to permit running more than one ASIO enabled app and for some routing flexibility.
 
I've done all the workarounds to loopback audio into Reason.  Most of those solutions are about as useful and surprisingly similar to learning to chew your own toenails.
 
The most useful way of integrating Reason's workflow into Sonar is done by using Rewire in the way it was intended with Reason as the slave and Sonar as the host.  If you spend as much time working out how that works as you would using any of the workarounds you'll find it's a great match.
 
Using ASIOLink or an Audio Hardware Loopback I can get the latency nicely low but why would I want to jump through those hoops when there's a perfectly accepted way of working with the two programs.
 
It is perfectly possible to send midi from Reason to Sonar however whilst Rewired using the EMI in Reason and virtual (or real) MIDI cables to trigger as many VSTi's in Sonar as you like.  There is no penalty for doing that other than Sonar will be rendering the audio which is certainly no hardship. amd of you want to keep the Reason project self contained just bounce all the VST synths you ultimately want in the Reason project to printed stems and import them back into Reason if you so wished.

Jonbouy:
 
If I were the primary user attempting to incorporate VST's into Reason, I would agree with you wholeheartedly and adopt your recommendations. However, my query was for the benefit of my wife, an experienced Reason user who knows nothing of Sonar and isn't even curious. Thanks for the thoughtful practical reply, though.
 
Keith

subtlearts
It was and is fiddly, but possible. I had it working under X3 last year - full bi-directional control with both programs running (Sonar as host, Reason as slave), sending MIDI and audio in either direction, however I wanted to. Round-trip latency was even manageable, not brilliant but not crippling. But it took a bunch of brain-befuddling workarounds to get it happening, and I never ended up using it for anything in a production sense. Just one of those technical mountains one climbs "because it's there"... wait, does anyone else do that?

Guilty as charged