What should I buy to replace my Herron VTSP 1

The Herron has gained the reputation as an excellent sounding and performing tube preamplifier. So moving to something else may simple become change for change sake, which we all sometimes want or need. Personally, I have a few ideas, but want to hear a bit more from you, first, if possible.

Where do you currently stand in terms of sonics, and what sort of change would represent an actual and successful upgrade? Also, what power amplifier and loudspeakers do you have?

i'm not sure I can answer all your "sonic" questions intelligently. I have Aerial 8 speakers and a Rogue stereo 90 with super magnum upgrade. The herron is a nice pre. i don't know that i'm setting out to upgrade or just "change" as you suggest. the thing i don't want to do is go backward. i want nice quiet, good separation, neutrality. I want a nice deep bass extension without booming. when I ask a question like this I guess it helps if a person owned one and made a move and was really happy.

I think you put forth a very intelligent response, and make a lot of sense.

Although probably the most ubiquitous, 6922 based preamplifiers often sound less romantic and fleshed out to me than other implementations, and can lead to not feeling comfortable with the overall sound.  Have you tried any 6SN7 preamplifiers?  After hearing them, you may also prefer that type.

Also, a bit less conventional, but the sonic attributes you mentioned might lead you to try a solid state preamplifier.  So long as you keep that Rogue power amplifier, you'll still enjoy the good things tubes provide.  After going with the tide for a very long time that says tube preamplifier and solid state power amplifier, I believe the opposite sounds best, provided the match with the loudspeaker works.

Regardless of how you want to move forward, I think you can get a manufacturer or dealer to allow you to try their product without risk