Old Krell vs new Krell amps...

I think it's more a matter of taste. I've been told by Krell employees the FPB series is better than the KAS amps. I haven't listened to the Evos.

IMO, the older Krell KAS-2 mono amps are not Krell's best sounding amps, not by a long shot. Krell made a major step forward with the FPB series of amps. Therefore, if the newer Evo amps are at least as good as the FPB amps, then I would definitely opt for the Evo series.

I've upgraded to a pair of Krell Evo 600 from a Krell 700cx, and I love the new Evo series. The Evo series is more of everything: transparency, imaging, dynamic but the thing I've noticed the most was that the Evo series is very smooth which makes the older cx series grainy sounding. However, if you haven't heard the Evo line then the cx series would sound perfectly fine too.
So go for the latest series if you could is my opinion.

First of all, I have never heard the KAS amps. I have owned the KSA (150 and 200S) series, the FPB300c, then the FPB300cx and currently the EVO302. The 300c was good but the 300cx was far better, i.e., difference was very large between the "c" and the "cx" version. The older KSA (not to be confused with the KAS)were extremely grainy and not very reliable in my opinion. Finally, the EVO302 is significantly smoother (less listener fatigue) and has very, very impressive bass (perhaps since it is mated the the EVO222 preamp) making it sound much better than the cx version. Among the EVO, I recommend the 302 over the 402, since the 2-channels appear separated better in the layout of the 302 and this is reflected in the performance (maybe I am biased). Bottom line- if you can afford it, go get the EVO302 or economise and find a 300cx or the 400cx. Regards

Thanks for all those answers : they are very interesting !
I think that the best choice would be a new EVO 302.
The KAS and KAS-2 are old amps and reliability problems could occur fast...
I noticed too that the EVO 302 construction (layout) seems to be more "clean and symetric" than the 402.
In the 402, the two output stages with their dissipators are parallel and very close.
In the 302, the output stages are on each side, like in classical stereo amps.
Upgrade1394 : could you confirm me that they are actually 2 transformers in the 302 : a smaller one upside the big one (that is shielded) ? Another question : do you have compared your EVO amp with some Pass amps, like the X350.5 or the XA100.5 ?
Best Regards,