Huge volume differences between various VST synths

Bit - like you I have a technical background.  I understand that patch to patch variances will be high.
 
But this is something endemic to some of the plug in developers.  
 
Arturia is always WAY low volume vs everything else.  XILS too.  
 
I am sure there is a lack of a a standard.  It would certainly be nice to have maybe a +/-3 dB variance tho.  12 seems so high.    

I don't have any of those synths. What levels do you see at the default master volume setting?
 
I usually have the opposite problem: my primary synth is Zebra, and every time I browse patches I have to turn the volume way down. My secondary synth is SynthMaster, and I have to turn it down some, too.
 
My Spectrasonics synths (Omnisphere, Trillian, Keyscape) are similar but not as extreme, and usually require turning them down by about 6dB. At least they're consistent within their own product line, which suggests that Spectrasonics at least observes some in-house standard.
 
And don't get me started on the lack of level consistency in the Kontakt world!

space_cowboy
Bit - like you I have a technical background.  I understand that patch to patch variances will be high.
 
But this is something endemic to some of the plug in developers.  
 
Arturia is always WAY low volume vs everything else.  XILS too.  
 
I am sure there is a lack of a a standard.  It would certainly be nice to have maybe a +/-3 dB variance tho.  12 seems so high.    

Volume variation between synths is present in hardware instruments as well. Some are easy to configure to give an output hotter than the +4dB standard, some always a bit low for -10dB "consumer" levels no matter what the patch.
 
Trouble is that a volume shift of 3dB in output is nothing. If you've one oscillator running then adding another at the same volume is going to give you +3dB, a third another 3 and so on. And if the added volume from the oscillators pushes the filter into resonance then with many synths that will add yet more volume.
 
For what it's worth, the times I use software synths I generally find I have to reduce the channel volume or the synth output volume. If anything I find they tend to start too high. An approximate standard might be useful, but it would have to be defined carefully - "one oscillator, sine or triangle wave, filter fully open, no resonance, amplitude envelope sustain at maximum" might do as one, but how often is such a patch used in the real world?