I love black people too!!!!
Basically most of the tube hype is pure bullsh*t. I'm not very good at all this technical stuff, but I'll try my best. Somebody please correct me where I am wrong. Here's the deal, there are two standard ways you can amplify a signal: tubes or transistors. Tubes are an older technology. They are very inefficient and distort on the first harmonic, but it was the only way of doing things for many years. Then transistors came along. Transistors were supposed to be a better technology because they distort on the second or third harmonic rather than the first and they were much more efficient. They are also cheaper to produce. So everyone in the audio community thinks transistors are hot shit because they pass a more acurate signal and all that cool stuff.
Then why does everyone want to stick tubes in everything now? Well, there are a couple of reasons. Tubes distort on the first harmonic, but many people find this to be a desirable and pleasant thing, even though it is less accurate. Tubes also take clipping a lot better than transistors. You can "push" or "drive" a tube amp beyond it's capability and it will produce a pleasant natural distortion. This doesn't sound as pleasant with transistors. The "retro" thing is also very popular right now so many people are trying to reproduce sounds of eras when tubes were the norm.
The silly thing about all of this is that it is not really relevant to the world of the home recordist. First of all, good solid state gear is a lot cheaper to produce than good tube gear, so you are going to get a lot better sound out of your budget solid state preamp than you would a budget tube preamp. Almost all of the gear that sells for under a grand and has a tube in it is a gimmick and a waste of money. Home recordists often find that the stuff they record sounds tiny, harsh, brittle, cold and a number of other catch phrases. They mistakingly think that using tube gear can "warm" up their sound, when really the fact is that they are just crappy engineers using crappy budget gear and sticking tubes in it is not going to help a thing. Some of the most elitist sought after preamps, like Neve, are solid state and you won't find anyone saying they sound tiny or cold.
I don't know where this whole myth got started, but I think it has something to do with guitarists. You see, guitar amps are about the only exception to this whole thing. Since guitar amps are almost always pushed to clipping and even beyond to high levels of distortion, it only makes sense that tubes will sound better because they produce a much better clipping sound. So every guitarist knows that if he wants his guitar to sound good he has to use a tube amp. I think this philosophy just got carried over to home recording when guitarists started laying down licks on their portastudios and wanted it to sound better, so they figured they needed tubes.
I'm not a computer programmer so I don't know how the tube plugins work, but imagine the more expensive ones probably use some sort of mathmatical algorithm to replicate the sound of a tube slightly clipping or distorting on the first harmonic. The cheap ones probably just act more like a low pass filter to nock some of the harshness off the top end.
The whole analog vs. didgital thing is an entirely different topic that has been discussed frequently on these boards.
