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,