In Rev 3 the I added a shunt regulator driven by a CCS on the driver stage. This rates as one of the biggest improvements so far. The dynamics are really wild now. The background is blacker than ever and I'm hearing things I've never heard before. Bass has taken on a whole new personality, it feels totally bottomless. Kick drums are great. This is a SET that never looses it's composure no mater how crazy things get.