How do I smooth out violins?

Power conditioning on the front end will indeed make a big improvement in this area. I have tried many and always come back to a BPT balanced power unit. I am continually amazed on how much the BPT improves the music in my room.

Great on a digital front end. Removes glare, noise, sizzle in the upper frequencies, separates out the instruments in their space ....etc

I use a BPT 3.5 Signature. I cannot overstate the impact. Mixed bag on amps, but a must on a digital front end and preamp.

Get better equipment or roll off the highs.

Put some DNM reson speaker cable in place of AQ4, will probaly do it for under 200 bucks.

Some very good suggestions and I agree that you should have a reference CD. That said, when I mentioned earlier that I changed my cables, it was the final step to my system.
I agree with those who say start at the source which is your CDP and next the preamp. I also agree that all systems need power conditioning or filtering (I use a Furman), but I think you can find the cause of the harsh highs before heading down that path.

Charles1dad, I disagree with almost everything in your recent post. Take another look at the system in question.

What if only one recording sounds good with a given system? Shoukd you only listen to one recording or do you want to enjoy your music collection?

If there is a need for a line conditioner I am all for it, but not everybody needs one. Also, if the system is not well assembled a power line conditioner is infact a band-aid. Once again take another look at the system in question. Does this look like a well matched system to you or do you see room for improvement?

Your approach of only listening to "Audiophile Approved" recordings and wasting money on a line conditioner is very bad advice.