Preamps waste of money?

I've been forced to reevaluate the role of preamps. The best sound I have achieved is result of adding a stepped resistor volume control at the input stage inside of my tube amp. All other options I have tried or auditioned including both active and passive volume control(autoformer and LDRs)have "colored" the sound in one way or the other to an unacceptable degree compared the stepped attenuator at the input. Has anyone had similar experience?