Why does my system now have shrill top end.

I havd been personally working on 2 specific areas to address digital  if you have a player, or dac the cable  possibly warmer meatier. My cables are all set totally happy with the Unique Verastarr cables.  I have a different type of Loudspeaker that gives you options for example in open baffle  I can put whatever 
Brand components in the cross over I currently have a 1 big Clarity 
Capacitor for the midrange. Duelund just came out with a less expensive version 
Of their top Cast cap except with a smaller Aluminum case vs 
The Big paper case hd JAM cap. Sonicy this cap feeds directly just the mid range in the Voxativ driver . This eliminates all excessive CD brightness from bad recorded digital. The  $400+ dollars for 2 caps sounds like a lot of money  but far cheaper then s stack of fuses csbles or a component -and a huge dividend in warmth depth and musicality .their new 
Silver wax oil .01  bypass caps put in amps,preamp digital is another worth wild venturefor less thrn s good fuse each.the new Duelund Jam capacitors. 
You will be hearing a Lot more on these one of the best in the World by far the biggest impact . They do take some 400 hours .
I am just letting play got 3 weeks straight.Shoot for at least             5-10 %capacitor value to use Minimum, more if you have small values and room .3.3uf is max size on Jam caps they pack a punch.

Having all the fuses and cables in the right direction helps a bunch with that sour and harsh sound. Harshness is one of the traits of incorrect direction. Too bad most power cord manufacturers don't subscribe to the idea of directionality. Oh, well, so it goes.

I would seriously look at the amp. High end harshness is a symptom of a class A amp starving for bias. Does the amp run as warm as it usually did?

Plus one for electrical issues in your new kitchen.  I would try listening to your system with the new kitchen fully operational as a baseline, then try:

1. Turning off all kitchen lights - listen
2. Turning off all breakers to your new kitchen (if possible) - listen
3. Try plugging your amp into P5 with all kitchen electrical devices on including the lights - listen, then repeat 1. & 2. above with amp plugged into P5.

This should tell you if something in the kitchen is the culprit, and if power conditioning is helpful.  If you do not already, you may want to put your system on a dedicated AC supply line(s) and breaker(s), especially if as has been mentioned it now shares a line with the kitchen or some other potentially offending circuits as a result of the new construction.

My main system is on a dedicated 10 gauge supply line with its own 30amp breaker.  I have a dimmer in the listening room (with incandescent bulbs), but it is on a different circuit.  Amp plugged directly into wall with no direct filtering (but do have a conditioner plugged into the same socket for sources) and system is dead quiet, treble never sounded better.

Good luck!