I like the JT4000 overall, but there are a few things to keep in mind. First, the output level is quite low—you’ll need to run it through an amp or boost the input gain on your interface to get an optimal signal. Additionally, the placement of the USB-C and output ports is a bit inconvenient. With the audio jack plugged in, there’s very little room to comfortably tweak the cutoff knob, which can be frustrating during use.
On the positive side, the sound quality is solid, and all parameters are fully MIDI-mappable. I was able to set up a custom user mapping on my Arturia KeyLab Essential using the Arturia MIDI Control software and the CC values from the manual, and it works flawlessly. This makes it easy to integrate the JT4000 into a DAW or control it with another keyboard.
One small drawback is that you can only use one oscillator in "Supersaw" mode at a time, which was a bit of a letdown. However, considering the price, it’s hard to beat the value this synth offers.