Komplete Audio 6 & System Output as an Aggregate Device

Hello.

I am running OSX El Captain 10.11.2. I have an iMac 27" Mid 2011. I am using a Complete Audio 6 interface. I have two KRK Rokit 5's, and one KRK Rokit 10 (I am aware - unusual set up). Apologies in advance if my laymans terms' are confusing.

I am having a bit of strife trying to develop an Aggregate Device on using Audio MIDI Setup that will run audio down all channels.

When I attempt to create an aggregate device, I am able to do so. I select Built-In Output and Komplete Audio 6, however my problem arises when I try and run audio content from the system to my Komplete Audio 6 and Built-In Output. It simply will not run them both together at the same time.

If I check Built-In Output and check Drift Corrector it will not play any audio to my KRK Rokit 10 (which is connected via a TRS Cable to my iMac's AUX port).

If I check Complete Audio 6 it will play through the Complete Audio 6 interface to my two KRK Rokit 5's which are connected to the interface via two TRS cables.

If I check Complete Audio 6 it will play through the Complete Audio 6 interface to my two KRK Rokit 5's, and then if I check the Built-In Output it will not play through to the KRK Rokit 10 (which is connected through adaptors to the AUX port).

I'd be grateful if you guys could give me some advice as to how I might circumvent this (if it's possible). Of not is the fact that my AUX to TRS Adaptor uses SPDIF Female cables, which divide into two separate (I presume Left and Right channels) then connect to two male SPDIF cables which then change to two male TRS cables (which then connect to my KRK Rokit 10's).

I hope my prose is not too confusing, and I hope to hear back from someone soon. 🙂