The Korg NTS-1 is a monophonic, multi-fx synth you build yourself. I have been personally using this as an external FX engine for my Microkorg XL+ with a ton of success. The NTS-1 takes 3.5mm input from any source, and allows for FX processing then outputs through a 3.5mm. There is also TRS Midi ports for use with external Midi Gear. It is powered via micro USB, and can be powered with an portable battery pack or USB outlet. This really adds to the portability of the NTS as it can be added in with pocket operators or velcro’ed on top of other synths.
You can put this in the middle or end of nearly any chain and it will sound great! It has Delays, Modulations, and lush Reverbs. What really opens up this unit is the ability to use the Multi-engine FXs that are present on the other Korg Synths (Minilogue XD, and Prologue). I will be posting some new NTS content soon.