Logic Pro 8 The Odd I/O discussion


New Member
I am trying, for the first time, to use Logic 8's I/O plugin and I'm slightly baffled as to how it works.
I know that it routes audio to the outs of my interface and then accepts the audio back on ins but, for some reason, it's behaving erratically.
Here's my set up:
My interface is the Focusrite Liquid Saffire 56 and I want to patch in an SSL Buss Compressor on an Aux so I can mix with Buss Compression across all channels.
The compressor is attached to a patch bay along with a load of other gear and 8 outs and 8 ins of my interface.
I have routed the output of my audio tracks to Buss 1 (Aux 1) and then inserted the I/O plugin on the buss.
The interface outs that correspond to the patch bay connection (half-normalized) are 5 & 6, so I duly put 5 & 6 into the output section of the I/O plugin.
The SSL Compressor returns correspond to inputs 7 & 8 on the interface, so this is what I put in the input section of the I/O plugin.
Nothing....not a sound.
Whereas if I put 7 & 8 as both the input AND output on the I/O plugin, it works!

Anyone have an idea of why this might be the case? Anomaly within Logic? Or perhaps it's just me being stupid and missing something obvious? Or do you think perhaps I have set up the interface incorrectly?

I'd really like to clear this up as I have a lot of other outboard that I would need to use on a daily basis and want to make sure I'm doing everything right.

Many thanks in advance for your help.