Within a couple years of getting into guitar, I picked up a Digitech 2120, which was my first introduction to tubes. Funny thing is that I didn't know about tubes or care about them at the time. I ended up trading the unit and getting an ADA MP-1, which sounded much better and was certainly more tubey than the Digitech. The ADA was capable of tones that the Digitech just could not do. I ended up selling the ADA to a friend who I was trying to get into guitar.
My first real tube amp was a Fender Blues Junior, which produced cleans that made keenly aware of how great tubes could be. Even with some descent pedals, I just couldn't find a nasty distorted tone...until I discovered the Mesa Boogie Studio Preamp with a Mesa 50/50. Playing through that wicked combo turned me on to Mesa Boogie.