@Wizard- email me sometimes using the forum email tool so we can discuss the tube line drive preamp. There are some things you'll need to know about it if you end up taking it. I can't recall what tubes it uses but they are a Chinese or Russian new production equivalent to one of the common current drive preamp tubes like a 5645, 12AU7, or similar. It can be modified to accept different tube types pretty easily as long as the pin out is the same (filament heater, anode, cathode, screen, etc). There is a great website you can cross reference tube types to find out what other tubes have the same pin relations. From that you can make a list of tubes you can experiment with. Some are drop in substitutes and others will require a little adjustment to the cathode resistor value. It's a great platform for testing and modifying a simple tube circuit of this kind. I believe it is a zero voltage gain circuit and only increases the current forward (decreased Z-out for driving low impedance inputs like certain amplifiers and headphones). IIRC its a really nice circuit with low odd-order harmonic distortion and a small amount of second order harmonic distortion. It's this second order harmonic distortion that is what some say gives certain tube circuits their "tube like" or "warm" quality. I don't want to wade in too deep here on this topic, there is much controversy on audio forums about this subject. So, if you're not much into tube audio this is a great starter circuit that should prove to offer hours of tweaking fun. You may have more knowledge about this subject than me but I wouldn't assume it. If you're a tube virgin then the best place to plan on using this is between a digital signal source like an iPod or CDP, and your amplifier. It should add some character to your sound system, whether it's good or bad only you will decide.
I've got some old transformers laying around too that would probably work for this. If you need one holler at me and I'll see what I can dig up. You'll need to build an ultra quiet power supply too. I can whip up a circuit on paper for you if you need one, I've got a software program that models power supplies for tube circuits. That and a 50-100k stereo pot and a little wire and some connectors and you'll have a very cool little tube line drive preamp that will be a great conversation piece.
Let me know if you get it!
JM