I also agree that a new preamp would be the best place to start. For 2 channel, its just too important to not get right. Both the Cary and BAT units mentioned above are excellent. Either will completely transform the sound you get from 2 ch. Another unit you may want to consider is an Aesthetix Calypso. Its also a great all around, excellent sounding component. Its good enough to be your last preamp.
The only thing I would add is with regards to tube rolling. There's nothing wrong with doing it, but I wouldn't lock myself into a choice primarily because of it. The people who design the preamps mentioned above really know what they are doing. They all sound great with stock tubes. I would suggest that it may be better to choose a preamp in its stock form. While the sound of the tubes do factor in, the design does, as well. If this is a component that you plan on keeping for a while, I think you will probably make a better choice going that route.
That said, I think it would be pretty difficult to mess up with the 3 preamps listed above. If you don't mind going SE, Conrad Johnson is a great choice also. As far as the amps go, stick with what you have for now. Your system will sound vastly better with the right preamp. Also, you will need time to get used to the sound and if you change 2 major components at once, it increases your chance of making a mistake. There's a very good chance you would pick a different amp later on, once you get to know your system, than if you were to buy one right now.
