The above is a stylised schematic of the audio routing — none of the MIDI routing is shown, nor are any of the MIDI only devices (keyboard, controllers, etc.).
The laptop feeds eight ADAT channels to an external audio interface.
The ai feeds them on to a D/A breakout box with eight balanced line outputs. CH1/2 go to the studio monitors, CH3/4 go to my headphones (not shown), CH5/6 go to one of two 10-in/4-out mini-mixers, CH7/8 go to an outboard fx chain (including a KAOS Pad).
The two mini-mixers take additional unbalanced line inputs from two CDJs, a Blu-ray player, a VCR and sundry games consoles via an A/V multiplexer (represented by a single gamepad in the schematic) and forward them on to a DJ mixer.
The DJ mixer pumps an unbalanced signal out to the amplifier, two booth monitors (not shown) and a balanced signal to a AD/DA interface with eight balanced mic inputs, eight balanced line inputs, eight balanced line outputs and an eight-channel ADAT I/O interface.
The outboard chain feeds into a direct interface box.
The di box balances the signal and feeds it into the AD/DA interface .
The AD/DA interface feeds the ADAT signal back into the external ai.
The ai then feeds that back to the laptop for mixdown.
Okay, well, so far so good — I can sample from any source (TV, Blu-ray/DVD/CD, VCR, games consoles), record DJ mixes, and have six balanced line inputs to spare … route the signal to the amp for listening, or to the laptop for recording … play whatever project I’m working on in my DAW on the studio monitors, headphones or even the amp … route all of it through the fx chain … and all simultaneously (assuming I don’t need more than two hands to do it).
But the fx chain is a little limiting: what if I decide that I absolutely must rehearse (a studio, not a DJ, set) and, what’s more, I want to remix stuff on the fly … so, I’ve decided that I absolutely have to fiddle about with the KAOS Pad live as well — MIDI cc/sysex messages won’t do, I want to wipe my greasy fingers all over it, swamp the sound with amateurishly excessive amounts of reverb and make a trainwreck of things with ill-considered delays.
And, furthermore, I don't want to listen on the studio monitors or the headphones: this is live, man ... there's such a thing as artistic integrity, you know; I won't be able to rely on them when I'm onstage in a condemned building on an industrial estate in the middle of nowhere ... and, what's more, I probably won't have the rest of the outboard chain available anyway — I need to re-create the IRL ambiance when I rehearse … get a feel for the sound in a room, not the studio.
And I want to be able to record the performance as well — you never know, it might be a good one and I could release it as a ‘live’ mix (or even album).
I don't want to be un-/plugging cables either— that would be tedious.
So, I need to split/mirror the signal from the breakout box CH7/8 pair, so that I can bypass the rest of the chain and feed from the KAOS Pad direct to the di box when I want to rehearse, but recombine them when I want to go back to the full chain.
I need to be able to route the signal in all of the following ways, without having to un-/plug stuff — the below shows only the logical aspect, of course, not the physical (there is only a single physical L/R input pair between the chain and the di box).
Unfortunately, whilst the I/O interface is a AD/DA unit, the analogue inputs can’t be routed to the analogue outputs, only to the ADAT interface … and mirroring the D/A breakout box to the ADAT in would result in a recursive summing/feedback loop, so that’s not an option either.
Having given it some thought, therefore, it seems clear that the signal path needs to be as follows:
The breakout box CH7/8 pair needs to feed into the KAOS Pad.
The KAOS Pad needs to feed to 2x splitter/mirror cables, forwarding one L/R pair to the rest of the chain and the other pair to the di box.
The rest of the chain should route an L/R pair back to the di box as well.
Hmmmm ... I don't want feedback/recursive summing though, so the two subchains (KAOS Pad alone and KAOS Pad+chain) need to be switchable.
Okay, well, if I'm going for switchable, I might as well be able to put the KAOS Pad before or after the rest of the chain as well ... so, I need to split/mirror the output from the chain and feed it into both the di box and the input to the KAOS Pad.
But, once again, I don't want an infinitely recursive loop of KAOS Pad to chain to KAOS Pad, so the inputs need to be switchable:
The breakout box CH7/8 pair should feed into a switchable input along with the output from the chain, meaning I can route the audio to the KAOS Pad or to the rest of the chain.
The output from the KAOS Pad should be switchably mirrored to the di box and the rest of the chain, so the signal can go from the breakout box to the KAOS Pad and then either via the rest of the chain or bypass it entirely.
The output from the chain needs to be switchably mirrored to the di box and the KAOS Pad, so that the signal can
1. route via the the KAOS Pad and then rest of the chain
2. route via the rest of the chain and then the KAOS Pad
3. bypass the KAOS Pad altogether, going via the rest of the chain only
It's a simple enough proposition, requiring just three switchable splitter/mirror nodes: one before the KAOS Pad/rest of the chain, one after the KAOS Pad to enable bypassing the rest of the chain. one between the end of the chain and the di box to simply send the signal on to the laptop or else forward it to the KAOS Pad ... so the one before the KAOS Pad needs to be able to take at least two L/R input pairs and have at least two independent L/R output pairs in order to prevent feedback/summing of the signals (it needs to be able to take the input from CH7/8 and from the end of the chain).
But thinking about it, if I'm looking for flexibility, what if I decide I want to be able to bypass individual elements of the rest of the chain as well? Or, better yet, reconfigure it at will — I might want to put the reverb unit after the delay or vice versa … or the compressor before one or other of them rather than as the final stage in the signal path … or not compress the signal at all, whatever takes my fancy.
So, the above schematic needs expanding, to include the extra routing options.
I really don’t want to go to the lengths (or, more importantly, expense) of getting yet another I/O interface (never mind another three additional mini-mixers), if I can avoid it, so, your task, is to tell me what else I could use in order to enable the reordering of the outboard hardware chain on the fly ... routing the signal between them any way I want and bypassing whatever bits of kit I don't want to use ... without ever needing to unplug anything or creating a feedback/recursive summing loop … and keeping the signal path balanced, if at all possible (there’s only so much noise the di can cut and every extra device doesn’t help it do that).