I am using cubase vst 5 and have various direct x pluggin effects such as Aural Activator, Harmonizer, Pitch Shifter etc. Are there any pluggins that you can use for vocals that give you that kind of valve amp tube sound?
Digital Fishphones- download all of these, they're free, and the compressor and distortion will help.
I have some more free VST effects that I've collected over the years, that might help if used right. I can email them to you if you'd like. I've found it's best to add these types of effects in very small increments, which over time will add lots of beneficial harmonics.