I mentioned the 'timing' thing only because I heard about an issue mentioned regarding another effect, and this was quite some time ago. Plus, I have never personally tested a 'send' to Nebula other than reverb.
I'm not exactly following what it is you're hearing that is too much. As for the sonic 'character' from the tape, well, much of that would be inherent ... however, a major 'user' influence would be INPUT level. To that, you could try lower your 'levels to tape', and then makeup the gain afterward. But again, not sure what the 'too much' is.
Really need more info from you, and what library and preset you're using. If you can describe what a particular preset is doing that you like or not. Tell us about it. We can all learn from other's perceptions and conversation.
thanks ive never used any effect as send with nebula other than reverb as well and just got word from Michael that he doesnt recommend doing this and " It is something that wouldn't work on the real tape machines as well and most likely it will reveal the tape machine's shift in information too much compared to the unprocessed signal" so think prob best leave this idea alone. when i said too much meant because of spectral reasons, meaning it changes the high mid or low frequencies too much. I use r2r and apex library, example would be like the more colored atr102-15 beautifull sounding program but as insert the overall sound is effected or "darkened" too much for my taste and some 30ips programs "brighten" too much for my taste on certain tracks where might want just want little of its flavor , neways imma try more cleaner tapes/options and diffent input levels like you suggested , thanks