Osquitar,
Im not sure if your original question was answered. If you purchase a tube amp you need a preamp to control the volume, unless your Integrated Amp (Rotel RA01) has the ability to be used as a preamp (it would have connectors (pins) on the back that would let you separate the amp from preamp) and run either amp or preamp separately of each other.
I do agree with Psychicanimal, the power delivery system is more important than most people realize and should be addressed.
Im not sure if your original question was answered. If you purchase a tube amp you need a preamp to control the volume, unless your Integrated Amp (Rotel RA01) has the ability to be used as a preamp (it would have connectors (pins) on the back that would let you separate the amp from preamp) and run either amp or preamp separately of each other.
I do agree with Psychicanimal, the power delivery system is more important than most people realize and should be addressed.