Is there Really a difference between a Krell 400xi intergrated amp and the newer Vandgard?


I currently own a Krell 400xi intergrated amp. It has 200 watts a 750k toroidal, balanced inputs, etc. Its very similar to the current vanguard intergrated amp in terms of similar spec's. I would like to know if anyone upgraded and if it was worth it? Is the sound different does it go lower, deeper, more of an open sound stage or should I just consider another route to improve what I already have.

thanks,

matt00
Really! , there is no tape loop or any thing like a tape loop on the vanguard when all past krell integrated's  had one,  I'm a huge krell fan, I  own krell now,  if the vanguard doesn't  have what's mentioned here,  than I may not be willing to use a vanguard,  to bad! 
I  believe I  will call my personal friend Patrick Bresnahan's personal cell phone and talk with him about this vanguard,  and see what modds are possible that can be done with the vanguard.
if vanguard so great,why there is for sale some used ones?:) And not so much krell fbi?I actually can’t find krell FBI for sale. I have krell kav500i.quite a good amp,indentical sounding like krell 250A and 250p combo,bass and soundstaging,espcially vocals are spot on