Upgrading to Duo 300 XD Stereo Amplifier and Illusion Preamplifier from Krell Evo

Definitely I bought mine a few weeks ago and don't regret it one second.  

I think the new Krell preamps are similar in sound to the older Phantom generation.  However, the new Duo and XD lines are much different sound than the Evolution generation.  The Evolution generation amps were very high resolution and very transparent.  Excellent if you wanted to get the most resolution and dynamics and transparency out of the sound.  The Evo and Showcase generation could be somewhat bright/harsh on some systems or speakers (but I think the Evo amps are excellent).  The new Duo/Solo and newest XD lines went more towards that very smoothed over Class A type of sound.  Very clean sounding, but colored with smoothed highs and mild/colored midrange.  You would really have to listen to it to understand what I'm trying to describe.  Many people love the new Krell amps, but it really depends on what kind of sound you're looking for.

My advice which I never seem to take is to keep and enjoy what you have. Your current amp and preamp are outstanding Krell products with beautiful build and sonics. If you’re satisfied now you might end up unhappy with the contemplated change which is going to cost plenty. I don’t know what else you’ve got but IMO new speakers would by far make the most difference in your system if you’re wanting something fun to change. 

Speakers are Harbeth 40.2 and the combo with Krell is superb. After 30 years of this hobby, I am enjoying the Harbeths more than any speakers I've owned in the past. I have had them for four years and have no desire to change.