How do I smooth out violins?

I have never heard your speakers, but this sounds to me like a speaker issue. Your speakers cross over from midrange to tweeter at 3 KHz. Its possible that your tweeters beam more than your midrange which would tend to make the upper frequencies stand out more. I have also heard harshness in some speakers at the cross over point. If you have a test disk that plays warble tones at various frequencies, it may be easier to diagnose if this is due to a tweeter beaming than with music playing. Just go back and forth between the frequencies above and below the crossover point and see if you notice a lack of coherence, that is, an obvious shift of sound from the midrange to the tweeter. My Magnepan 1.6QRs used to do a similar thing in the violin range where the violins would jump from the planar magnetic panels to the quasi ribbons. That lack of coherence drove me nuts.

Real 'live' violin sound is hard to hear listening to recordings, either massed or solo. To some degree you can simply charge this off to recording techniques, i.e. microphone placement. You usually are quite some distance from a violin when you hear it live, not so much with a recording where the mic is usually very near. Afar you do not get the highlighted upper mid range you often hear in recordings.

That said, many folks find tubed units can be helplful if for no reason other than tubes can have a more fluid sound. But violins can sound bright and etched using tubed units if you are not careful in tube selection, not a small chore in tuning you system. A 'warm' toned pre-amp will help, or if you go for an integrated, get one with an actual pre-amp with dedicated tubes, not just a passive pre and tubed power section which is very common, unfortunately.

Good luck. Oh, FWIW, I doubt that you will find the AAM3A a solution for your problem. Personally I'd get a tubed integrated as apposed to getting a tubed pre to match with a solid state amp. But thats just me. :-)