if your mindset is "I wonder what is the best piano that the Virus can do" then go ahead, knock yourself out.. but if it is "I want a realistic piano".. forget it.
PCM architecture synths do a fair/decent job on pianos, however their patches are based on samples piano wavs. one per octave at the low end and 4 per note at the high end.
A realistic piano require significant samples to do well.. 150-400MB is not uncommon...or, a complete architecture for modeling like the Roland VPiano.
if your mindset is "I wonder what is the best piano that the Virus can do" then go ahead, knock yourself out.. but if it is "I want a realistic piano".. forget it.
PCM architecture synths do a fair/decent job on pianos, however their patches are based on samples piano wavs. one per octave at the low end and 4 per note at the high end.
A realistic piano require significant samples to do well.. 150-400MB is not uncommon...or, a complete architecture for modeling like the Roland VPiano.
My mindset is more that first one because I know already that it's not possible to get a really realistic piano out of synths in general if you don't introduce samples to the patch as you said. But sure I think it's possible to get a piano sound out of a TI which actually makes people think "oh, that's some sort of piano for sure." All my attempts at this remind people of guitars or cemballos at first which is frustrating me, even though they seem to like the patches still a lot...
What I did with this patch you can hear in my first post is that I put osc1 and osc2 in wavetable mode, chose some waveforms which remind me of the decay of a piano, linked the waveform positions to an envelope so that it sweeps over time + introduced keytracking to both osc's waveform shape also to make them damp faster at lower pitches. Also keytracking with both filters to emulate more the fact that piano's higher note is more crisp than the lower notes, both in lowpass mode with some light distortion, etc, lots and lots of modulation and still not close enough to any sort of a recognizable piano...
Maybe this thread will help.
Piano sounds are quite complex sounds when you break them down. Hit one note on a piano, what do you hear?.. 2 or 3 strings sounding at once in slight detune to each other, then there's the resonance of each of those strings, and then the timbre of those strings, also, how hard the hammer hits the string, the decay of each string, and that's just for starters, you could go into harmonics of each string versus the wooden cabinet and harmonics that imposes on the sound as well... the list is endless.. however, if you synthesized each string and did a multi-layer of the piano you are designing, and thought about it and programmed each note individually and added detune, hammer action, decay etc, per string, you may get somewhere near, but then you would probably run out of polyphony/voices on your Virus, so... use your Virus for Synthy things and use Romplers/sample based instruments for piano's, each has their place in music, and one instrument doe's better than the other.. A Virus cannot do everything or every instrument. IMHO good luck 
Piano sounds are quite complex sounds when you break them down. Hit one note on a piano, what do you hear?.. 2 or 3 strings sounding at once in slight detune to each other, then there's the resonance of each of those strings, and then the timbre of those strings, also, how hard the hammer hits the string, the decay of each string, and that's just for starters, you could go into harmonics of each string versus the wooden cabinet and harmonics that imposes on the sound as well... the list is endless.. however, if you synthesized each string and did a multi-layer of the piano you are designing, and thought about it and programmed each note individually and added detune, hammer action, decay etc, per string, you may get somewhere near, but then you would probably run out of polyphony/voices on your Virus, so... use your Virus for Synthy things and use Romplers/sample based instruments for piano's, each has their place in music, and one instrument doe's better than the other.. A Virus cannot do everything or every instrument. IMHO good luck
Yeah yeah, emulating acoustic instruments with synth(s) isn't ideal if you're aiming for a realistic sound. However I'd be happy with a sound that reminds of a piano, not a complete copy of one. Anyways, I already found a quite good patch from the factory presets which I can use as a model to improve my own piano'ish patch so thanks for that, flabberbob. Ofc it's gonna get way too heavy for the synth if you're gonna emulate all the physics stuff a piano note consists off, that's not what I'm going for however.
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There's my patch's current mod matrix, that's not all of the modulation ofc because some of it is done on other pages but that's it in a nutshell anyways for anyone wondering what direction you should aim for when creating a piano'ish patch. As you can see, I've taken care of individual notes quite carefully but haven't gone too deep into the physics stuff so there's no emulation for as example hammer action or cabinet reflection stuff which makes the patch playable without having to worry about polyphony even with 2 unison voices.
The piano's hardware is pretty complex and cannot be modelled with common synth's architectures. Think only of the interaction of the strings within a triple string group especially when played in sostenuto mode. You will have to apply energy interchange effects. I did an approach using specialized equations in own DSP System taking such effects into account. The problem is the processing power and the money such a system would cost.
