Tube Amp give you more warm and rounded sound, a good tube amp can make your guitar sound a HUGE different. it depends on your personal favourite. tube amp are classified into many class, class A,AB,BC..... depend the circuit inside. Class A amp usually PTP designed with no PCB (all parts are not solided on a circuit board) tube amp usually use 12ax7 tubes as preamp, 6L6 6V6, EL34, 84 as power part (simply say), tube like light blubs, you need to replace them with certain playing time