I don't know about the hiss (maybe it's distortion - did you try to force the virus into sounding louder? or maybe input thru is on with lots of boost - check the config menu), but the missing notes sound like voice stealing to me. Are you using lots of unison with internal reverb and delay?
You can check the complexity of your patches (i.e. how resource intensive they are) by looking at the top right corner of the LCD screen, for each part. The more bars you see inside the battery-like symbol, the more complex is your sound, and the less voice count it will give you, especially when you multiply it by the amount of unison assigned for the patch. You can solve it by either simplifying your patches (reduce unison, shorten delay/reverb time, you can also eliminate them completely and use effects on your DAW. You can even try using less complex oscillator types); or by recording each part separately to audio, and mixing them from the audio tracks.
Hope this helps.
yes its voice stealing. : )
a short time later i read it in the manual, and all make sense now. i think the hiss is also from the overloading now it works fine.
im very happy with the VIRUS its awesome, but im sad because of these voice stealing effect, with software synthies like massiv or other you dont have this problem. and also i think its really sad that you only can add 2 aux channels (USB2, USB3) for separately channel function or how i should say 
my english isn't the best.
By the way, also a problem for me at the moment is side chaining. i use logic and the side chain window on the left top in the virus plugin works that only with a compressor as hardware? is there an easy way to side chain my sounds with this window there? or must i use the compressor for all 16 channels, also i have the 2 aux channel yes but i think you would get much out of your work with more, is there a way?
And a second maybe stupid question ^^' how can i use the atomizer. is the atomizer only for live playing? all my trys doesn't work.
with software synthies like massiv or other you dont have this problem.
This is because massive is basically a sampler and not a VA synth. Samplers are less CPU intensive, and even the hardware ones which are usually called "music workstations" have no problem reaching and surpassing a static 128 voice count. You should try loading a few VA synth plugins, and keep them all armed (because DAW-s can cheat and pre-record a VST's playback), and see how your computer copes with live playing.
and also i think its really sad that you only can add 2 aux channels (USB2, USB3) for separately channel function or how i should say
By the way, also a problem for me at the moment is side chaining. i use logic and the side chain window on the left top in the virus plugin works that only with a compressor as hardware? is there an easy way to side chain my sounds with this window there? or must i use the compressor for all 16 channels, also i have the 2 aux channel yes but i think you would get much out of your work with more, is there a way?
As I said before, you can solo Virus MIDI tracks and record them into separate audio tracks (this process is called bouncing) and mute the original. You can do all the effects and side-chaining on these tracks. If you find you need to correct something you can go back to the muted original.
And a second maybe stupid question ^^' how can i use the atomizer. is the atomizer only for live playing? all my trys doesn't work.
For the Virus, there is no difference between live playing and a DAW session because it runs on a different CPU than the DAW (the DSP-s inside the Virus), therefore it has no knowledge of what is going to be played through it. All you have to do is select the atomizer in the input section of VC (it sometimes helps to arm the track you use as 'sidechaining source' for the atomizer) and record a few MIDI notes within the octave range of the atomizer.
Good luck!
