What does moving from a 150 watt amp to a 400 watt amp get you?

Hi all, I’m coming back to tap the knowledge of the forum again.  I have a pair of revel ultima studio 2s that I very much enjoy. I’m currently running them with an Ayre V-5xe.  I’ve seen others say that these speakers need to be driven by 400 Watts to get them to sound their best.  I sort of understand the relationship between wattage and sound volume, but if I am not looking for “louder” what do I get with a more powerful amp?  I don’t hear clipping. More current?  But what does that do?  Sorry for my ignorance!
I use thousands of watts to provide clear sound for concerts I produce/mix, but have become part of the "Lower powered single ended tube amp cult," LPSEAC or as commonly called "lipseek" (you've seen the t-shirts, right?). By joining the cult you agree to a couple of things: You use efficient speakers (99db in my case, plus hundreds of watts in powered subs), and you collect tubes. For many decades (I'm 106) I've owned tubeless and tubed hifi amps with from 60 to 250 watts per side, biased class A-ish for at least the first few watts or something, and have enjoyed music spilling out of these things for years…but after joining the lipseeks I'm stuck. Nothing to my taste sounds better, clearer, or more emotionally engaging than a properly utilized group of single ended glass bottles shoving electrons around. Headroom SCHMEADROOM I say (as long as you use efficient speakers or sit with drivers a foot from your head). I haven't tried an OTL amp…yet...
Thanks for the peace of mind. Yes, they are P3ESR's. I'm glad to know the amp is enough.. watts really are a funny measurement.
Indeed. Your amplifier is more than powerful enough for the P3ESR. In fact, you will need to exercise some caution. You are fine. You did not say how large the room is, but if the room is medium size or larger, the only thing you could do to get a 'bigger'sound is add two small subs like the SVS SB1000 and an Antimode 8033 (but don't add subs if the room is small).
@wolf_garcia  You haven't lived until you've heard a pair of original Futterman H3AA's with KLH Nines or Quad 57's! Sublime musicality rarely equaled!