Updated: Mar 5
In this experiment, the objective is to try out the DI capabilities of the Helix for re-amping. In addition, explore the difference in sound quality between Helix input (used as a DI) and a Rupert Neve DI.
According to the Helix manual, this can be done as the Helix can send up to 8 channels via USB to your DAW, 2 of them being a DI pair coming from its guitar and microphone inputs.
So the direct guitar sound coming from the Helix can be recorded in your DAW and also sent back to the Helix for on-the-fly processing, and then via USB back to the DAW for recording of the processed sound.
As a second option, I will try to route the guitar directly to the DAW via a Rupert Neve DI, record the dry sound, send it to the Helix and then capture and record the processed sound on the DAW via the same USB method.
Configuring the DAW
Since I wanted to be able to output the mix back to my monitor speakers, I had to create an aggregate device to combine the Helix with my RME Babyface Pro in the manner shown in the picture:
As observed, I decided to preserve the routing of the Babyface by adding it first, and using it as a master for the clock to the Helix. So the USB input channel 7 from the Helix, which according to its manual is the Guitar DI signal, then becomes channel 21 in my DAW as the Babyface has 14 channels.
This channel's output is then routed to output 17-18 on my DAW which is equivalent to USB input 3-4 on the Helix. An important note is that this didn't work straight away; you have to manually set-up the Helix patch to receive audio from USB 3-4 instead of multi. I've achieved this making a 're-amp' copy of one of my favourite patches. The user manual states that you can leave the output as multi, but to be sure and avoid confusion with the analog Helix signal going into the Babyface, I've also changed the output to USB 1-2 only, which in my DAW turned into 15-16.
The next channel is to receive the processed sound. This of course will have to be set up to 15-16 (so it will receive the processed audio from USB 1-2 of the Helix, coming out of the selected patch) and then it can be routed normally to a stereo output for listening.
Note that software monitoring in the DAW has to be turned on, and the analog sound coming from the Helix into the Babyface has been disabled.
Enter the Rupert Neve DI
Once I got the above working, I wanted to compare the quality of the DI sound of the Helix with the Rupert Neve. For that, I've replaced the DI channel in the DAW (input channel 21 output channel 17-18) with an equivalent coming from the RNDI into the Babyface, and then out to the Helix as before.
Obviously, disconnected the guitar from the Helix and connected straight into the RNDI to record and make the comparison.
Both methods worked fine. The DI procedures in the Helix manual work as expected. Once that is set-up, creating the additional track for the RNDI or any other DI is easy, as long as you remember to route it to the Helix for processing.
Needless to say, the RNDI recording had a bit more body and sustain, as expected from a top tier DI. But the DI inside the Helix also worked well and both allowed me to record direct guitar sounds that I can now use for re-amping and post-processing at will.