UPDATE:
i've narrowed the problem of my bad tone down to the source.
it's my Zoom 505II. i thought that it was just providing me with gain, but to my dismay, when i changed amp models, i noticed it was giving me a horrible cheapo amp simulation.
what would you suggest me do now? still go for the amp? or get a good distortion or amp modeler? (namely the Behringer GDI21, because i love V-Tone modeling)
thanks, BM