Questions about Preamp Tubes

Hi,

I was thinking of buying a preamp (tube and SS). Will the tubes need constant replacement? If yes, then I would rather just use SS preamp to save myself the trouble/cost. My understanding is that it becomes very, very hard to differentiate between tube/SS in high-end products; however, is this the case in lower-end models? Will it still be the case in cheaper/older preamps by Audio Research and Conrad Johnson (those were the ones I was looking at)? Obviously I will try to try any preamp out if possible to test for synergy, but I don't want to consider tube preamps at all if they have the above problem.