When controlling a hardware synthesizer from Touché, we would always recommend to use the MIDI Out jack on Touché together with the included adapter and a regular MIDI cable and hook this up to the 5pin DIN MIDI In of your synth. This is the most reliable procedure and it is explained in detail in the following article/video: How to use hardware presets
However, it is also possible to use Touché to control hardware synths directly via their USB MIDI interface. For this, we need a device that offers USB host functionality. In most cases, this will be your computer, but sometimes you can even hook up Touché directly to the device you want to control, just using the USB cable.
If you want to use Touché to control some external instrument via USB MIDI, you must use the MIDI re-routing function of your DAW and select the CCs you want to control by using a hardware preset in Lié.
As long as Touché is in Slave Mode (connected to Lié), it will always send MIDI CCs 16/17/18/19 via its USB port, because Lié needs those CCs to speak with Touché. Even if a hardware preset is loaded in Lié, Touché will continue to send the default CCs to Lié, but Lié will translate those to the CCs that are specified in the selected hardware preset (compare the video tutorial Signals sent in Slave Mode).
In order to send these transformed MIDI CCs to some external instrument, you will need to create another MIDI track and choose "Lié" as MIDI input for that track. You can then use the 'MIDI output' or 'MIDI to' field to forward the incoming MIDI from Lié to your hardware synthesizer (or any other device that's available to your DAW). Here is an example with Ableton Live and a DSI Tetra. For other DAWs, the workflow will be similar.
https://www.dropbox.com/s/8gccqxw6zxyrtrb/Li%C3%A9_Live_USB_HardwareSynth.mov?dl=0
Please be aware that the forwarding of MIDI messages as described above will only work with the VST version of Lié. It isn't workable when using the AU version of Lié due to an inherent limitation of the AU format.
These days, more and more devices for music production offer USB-A ports that enable you to hook up external MIDI controllers directly via USB. USB-A is the very common, flat and rectangular port that you find on your computer as well (or used to find in times before the spreading of USB C). Sometimes, this port may only used to accept storage media, so look out for "USB to device" ports. Examples that do have such compatible USB-A ports include Korg Kronos, Akai MPC One, Yamaha Montage, Moog One etc. USB MIDI interfaces that are meant to be used in modular synths, e.g. the Polyend Poly 2, also feature this USB host functionality and USB-A ports.
Since Touché can act as a USB MIDI class compliant device, you will be able to connect Touché directly to these USB host capable devices just using the USB cable. Just make sure that the host device delivers enough current for Touché to work. Also, the USB host needs to be able to react to MIDI CCs or at least to pitch bend messages, or else hooking up the Touché would be an empty exercise to begin with.
Obviously, you can't connect Touché to your computer and to another USB host device at the same time. Therefore, Touché will always work in its Standalone Mode in these cases. If you want to adapt the MIDI CCs sent by Touché so they suit the CCs expected by the USB host device, you will need to connect Touché to your computer first. Create a hardware preset in Lié according to the MIDI implementation chart of the host device, and save this into the internal memory of Touché using the Memory View. This way, when connecting the Touché to the USB host the next time, you can use the preset buttons to recall the specific hardware preset that you want to use with the USB host.
Some USB hosts don't have a fixed MIDI CC implementation. Instead, they allow you to create CC parameter mappings directly inside the unit's operating system. In these cases, you might as well leave Touché with its default hardware preset (CC16/17/18/19) and create the parameter mappings directly in the USB host device. Modifying the hardware preset in Lié might still be useful though because Lié offers some advanced functions that may go beyond the possibilities of the mapping routine inside the host device (adapting dynamic curves and parameter range).