Upgrading 1500 Pre to 3000 pre.What Benifits?

What sonic differences/benifits can I expect upgrading Tube Preamps from The $1500 range(Music Reference,AI) to The $3-4000 range.Thinking of BAT,Supratek,or First Sound Presence Deluxe II.Amp is Music Reference RM-200 Hybrid/Tube.Small step up or Huge step up?Thanks Folks,JD
Whoooosh! went my system when I unloaded the ARC SP-11 for a BAT 50SE. Benefits: Resolving power, soundstage, vocal clarity, holography, sheesh, it goes on and on. Make sure your cables are up to the task when you get a new preamp though.

Auditioning is very important. Hook it up to YOUR system. The dealer should have in-home demo, or allow you to take it home with you(may require you to leave a deposit). Synergy plays a large part in high-end purchases. Also, not all $3k preamps are created equal, and some are clunkers. Conversely, some $1500 preamps will sound as good as some $3k ones and some $3k preamps may sound as good as some $7k ones. So pick one out that provides good value and has good synergy with your system. I won't make any specific recommendations because it's your decision.