Speaking of resurrecting this thread... ;D
Not sure how to get that tube sound in without a second computer; right now audio files, audio processing, & encoder all sit on the same computer. At no time does the signal leave the digital domain (although that could certainly be part of why I'm not 100% happy with my sound!).
Danny, you're the second person to catch it! Actually, I'm pitching everything up 2.2%, the rate the local "The Music You See On MTV / All Killer, No Filler" station used between '83 & '85.
If you grew up with 80s radio, I think the pitching up gives the music that "jump" or "lift" many of us remember from 80s radio (& earlier). If you DIDN'T grow up with it, it apparently sounds pretty silly (so I've heard).
I've seen some plug-ins that claim to create that tube "sound;" I assume they create those harmonics you mentioned, but I don't know if they do it faithfully or if they're just "distortion generators."
SEVEN DB of limiting!!! Holy crud! Talk about stomped on! I guess that's how they got the signal to "jump off the dial," though... wow... I bet I'm doing two or three db max, & it's all multiband limiting (except for a final dual-band clipper that is rarely hit, & only for a db or so).
Thanks for the kind words on the sound, too... I'm pretty happy with it now. I suppose like any engineer, there are days it sounds over compressed to me & days it sounds undercompressed, days of too much broadband gain riding, days of not enough broadband gain... knowing the limitations of my software, I'm pretty pleased. It's not an Optimod with an XT-2, but it celebrates its spirit, I think.