The whole point of the continued popularity of tube amps is to drive them too hard and get interesting noises ... people have been trying to duplicated that in digital for decades, and failed.
> people have been trying to duplicated that in digital for decades, and failed.
Because decades ago we simply didn't have the processing power to that kind of DSP.
Today, however, you carry that kind of processing power in your pocket.
It used to be really hard, because (amongst other things) the oversampling required to avoid digital aliasing. This is not really a big deal anymore, today. Also, it so happens to be the kind of calculation that parallelises very nicely.
I can really recommend this video to dispel the myths about what we supposedly can't to today in the digital domain: http://xiph.org/video/vid2.shtml (the guy also presents the matter really well, I found it very enjoyable to watch, even if I already knew over half the things he explains). To really make his case, he feeds signals to both a digital and an analogue frequency analyser.
They keep failing because they keep creating integrated "modeling amp" products which put the original amount of wattage in the back end, and that destroys the model at volume: you start hearing the break up of the back-end amplifier.
They are doing that to save costs: real tube amplifiers continue to be posed as higher end at higher prices.
A decently modeling amplifier would probably need several hundred watts, if not into the thousands, just to replicate a 50W tube combo at volume. The speaker cabinet and drivers would have to be different: high fidelity units, not guitar speakers.
I think people do get good results when they plug their modern amp modeling digital signal processors directly into a loud PA system, where the models find a decent amount of headroom and fidelity to reproduce what they are doing at loud volume.
If you just want "interesting noises" the VST plugin FuncShaper from Met-RS works great for adding distortion. It's a lifesaver on direct bass tracks. Pipe that thru a convolution of a good impulse response from a nice amp and you can't tell the difference easily.
