Trueno is a unique beast in several ways. Obviously the concept of putting analogue circuitry into a USB dongle and controlling it all from a VSTi is unique but so is the character of the sounds you get from it. It has a gritty character that you just don't hear in modern synths any more. Listening to the presets takes me back to the early 80s and the sounds I was getting from my Arp Axxe or Korg Mono/Poly. When you start to work on your own sounds, that character shines through even more. Even in paraphonic mode, where you only get one oscillator per note, the sound has a width and depth that surprises.
Another unique thing about Trueno is that it isn't just an analogue synth, it also has a range of digital (additive) oscillators available and you can edit them to create a virtually limitless range of oscillator sounds to work with. The way it works is definitely unique - the USB dongle generates the raw analogue oscillator tones and contains the analogue filter but everything else is done on your computer, via the standalone app or the VSTi plugin. So it's a hardware synth that can also be a bit of a CPU hog at times. Strange but true.
You get 3 oscillators and you can select from the three analogue waveforms - saw, pulse or triangle (plus noise on Osc 3 only) - or multiple digital waveforms on each one. Each osc has it's own gain control and once you get the gain above about half-way, it starts to overdrive the filter, which is where the fun really starts for me. It can get amazingly thick and nasty with little or no effort. The filter itself offers low-pass and band-pass modes and is flexible enough with resonance that is very controllable. Osc 3 can be used as an analogue modulation source, with limited destinations.
For such a small, clean interface, Trueno packs a lot of features. You get dedicated filter and amp envelopes but there are also 4 x modulation envelopes and 4 x LFOs, all with drag-n-drop assignment and straightforward control. It's very intuitive once you take 10 minutes to read the printed manual that comes with the synth.
It's not all roses, I've had a few problems where the sound starts to get distorted and the only way to fix it is to shut down Cubase and restart it. (Unplugging the synth didn't fix it.) It has only happened twice but it was a bit of a buzz-killer both times. That said, it's a small price to pay for a synth with such a great, unique character that is so much fun to work with, it's not even worth knocking a star off for.