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

Krellman is right. I have been pretty much a Krell user most of my time with this hobby (although not having the illustrious models Krellman has used) and the current Krell gear is very differently voiced from the older Krell gear. The Vanguard is in this new vein - more musical and forgiving, less visceral. Most importantly, the traditional bass slam that Krell is known for is no longer there. In the place of that is a more textured bass. Highs are slightly rolled off (not such a bad thing with some recordings), PRAT is no longer as good and the sharp transients and leading edge is much diminished. I am referring to the older main Krell line (and not the KAV line which sounded lighter and leaner). The FBI would still have the older sound. It really depends on what you like.

Just my 2 cents.

Excellent point- mikey8811
some of the newer Krell is made in china as well.

I finally talked to Patrick Bresnahan at krell,  he said the departed x president bill Mckeagan is what happened to the vanguard,  no pre-amp out,  no tape loop,  and ahh, the terrible voicing! , Bill did all this to attempt to save money and bill had the vanguard made in China! , my opinion,  what a way to shoot your self in the foot,  didn't save money,  promoted a lack of sales, and more than any thing,  no long term ownership! , have all of you seen the vanguard on the used market? , LOL!, there is no modification available! 

So what's the concensus here? , older krell sound vs the newest krell sound? 

First of all, the Vanguard and all their current line is made in the USA!  The older s-550 and s-300 and matching CD player were made in China.  As for the musicality, the sound is actually improved.  I've owned just about everything since the original FPB SERIES came out.  I call it exquisite neutrality with world class tonal reproduction.  Clarity and resolution is superb and personally, the bass surpasses the quality of the older design in every meaningful way.  As for the 400xi for example, it sounds broken compared to the Vanguard.  Not sure what you guys are smoking but it must be special.  It goes without saying that a great power cables are required, as well as great speakers and source.  Many mismatched variables can misdirect your assessment.  The Vanguard takes forever to break in and is meant for the 2 channel crowd like me.  I use a Krell Cipher and Krell Resolution 2 speakers.  Cabling and PC's are MIT ORACLE!  Also, the Vanguard is an updated design from the 400xi with a new preamplification stage and more storage capacitance, not a sea change.