The 9.0 to 9.2 is pretty subtle.... as you say, different power management that provides a smidge more meat when pushed, a slightly hotter input gain to make it easier to grind/overdrive with a lower output instrument, and slight revoicing of some of the voicing filters. I think that upgrade was designed as a minor, meaningful improvement without making the original 9.0 Shuttle obsolete. IMO, not worth upgrading, but a nice tweak for first time buyers.
6.0 to 6.2, all of the above, but with a significant revoicing of the low end, removing the attenuation of the deep low end that the original 6.0 had in place to optimize that head when matched with the small Shuttle cabs. So, while the 6.0 sounded very different from the 9.0, the 6.2 is basically a lower powered, less expensive 9.2, if that makes sense.
I was lucky enough to be able to preview the new 6.2 and the upgraded Shuttle 112 cabs, and it is a FANTASTIC upgrade, and would be a very significant improvement IMO for current 6.0 players, especially if they are using the original 12T.
Regarding SVT, like any amp, it is hard to make one amp sound like the other. However, JohnK and some other people very familiar with both amps have put up clips comparing the STreamliner with the SVT, and it is reasonable close (at least at the tone settings used.. So, of those listed, Streamliner by a WIDE margin. However, it takes quite a bit of EQ work, and of course, you will never quite get there. You couldn't make the SVT to sound like a GK or Genz either.... kind of different things with all these amps. I do find the Streamliner as one of the most realistic 'all tube amp' emulation though, along with the Mesa MPulse600 and the wonderful Walkabout. IMO there, and the all kind of 'sound like they sound' (including the SVT).
One thing for sure, neither the GKFusion nor the Shuttle amps have much in common with any all tube execution, and IMO are not even particularly tubey sounding compared to other hybrids like the Mesa, the Streamliner, etc.
Last edited by KJung : 01-06-2013 at 10:33 AM.