The web page mentions "three highly stable digitally controlled VCOs" and "we took a highly respected modular VCO design and adapted it for digital control" as well as "With the same oscillator circuits found in modular monstrosities". It also says "Trueno can tune all of its oscillators in 10 seconds" which implies that they actually need to be tuned. But "oscillator 3 has a digital noise generator", and there's the bit about digital waveforms.
Regarding the filter, it says "Trueno’s filter is based on a soviet Russian design known for its unmatched harsh, aggressive sound" which doesn't really say if it's an analogue design or a digital model of one.
Given that there actually seems to be an ADC in their, my guess would be that they are using some form of DCO design, i.e. digitally controlled frequency generation coupled with analog waveforms - similar to the way many what many would call analog synths generate their waveforms, from a Juno-60 to a Mopho. The whole tuning bit makes it sound like they are real VCOs though, with a DAC feeding them control voltages, possibly with the exception of oscillator 3 which sounds like some form of sample playback engine. This is all then coupled to an analog filter, before being A/D converted (so the VCA is actually digital) There also seems to be some analogue modulation routing, but LFOs and envelopes are digital.
The question is how much of a difference this makes, but there is one thing which definitely points to an analog filter: one of the modulation routings is filter FM, i.e. audio modulation of the filter with an oscillator. If you try to do this in the Axoloti for instance, you run into aliasing problems with the modulation, because the modulation will take place at the k-rate of 3 kHz, which is why this modulation path is fairly rare in VA synths. The Nord Modulars for instance have a k-rate of 24 kHz with a sample rate of 96 kHz, and I'm suspecting the same rates are used in for instance the Nord Lead 3 so it's less of a problem on that platform. For a really bad example of this problem check out the Oberheim OB-12. It sounds rather nice until one turns on audio modulation in the oscillators, when all sorts of nasty digital artifacts start turning up.
Now of course a true analog filter is not the only solution, if there is enough DSP power one could certainly imagine a VA synth where the k-rate equals the sample rate. But it does nudge me towards thinking the central signal path in this synth really is analog.
Then of couse as has been asked above in this thread, the question is, does it matter, in this day and age. Still, true audio FM is hard to accomplish on a VA platform without running into aliasing problems, and the Trueno designers seem to be aware of this and have tapped in on this possibility. (Note that they also don't mention oscillator FM, leading me to believe that the oscillators are actually DCOs.)
