I was trying to dial in a high-gain Euro Red Modern patch for a customer and the low end was flubby. I saw he had the MV at 4.0 or so and sort of dismissed it. I started tweaking and just couldn't get the low end right. The low end was thin but if I increased the Bass or Depth it got muddy.
Then I remembered that the MV seemed a bit high. I lowered the MV to 3.0 and raised the level to compensate. Much better. I lowered the MV some more to about 2.0. Perfect.
So, even though I've harped on this many times before, don't overlook your MV setting. Modern high-gain amps can easily push the power amp into clipping at relatively low MV settings. With the real amp it gets incredibly loud at those settings so you instinctively reduce the MV. In our virtual world we are unaware of how hard the virtual power amp is being pushed.
Did you use the Boost/Pad parameter?
See this:
http://forum.fractalaudio.com/axe-f...as-gone-up-considerably-14-a.html#post1018215