Getting rid of harsh, shrill treble

An SS amp is relatively unaffected by speaker impedance compared to tubes.
Your speakers are a tough load for a tube amp. I'd prefer 8 ohm nominal speakers with tubes. In any case, you are talking band aid solutions....the problem is your speakers....even the room acoustics should not make violins sound harsh and shrill. This is a well known problem for lightweight rigid drivers with small motors.

As you probably won't take this one piece of advice to heart and are probably on a road to spending $1000's of dollars on band-aids.....I beg you to spend a few minutes and google "magnesium cone ringing problems"....see for yourself....don't take my advice but form your own opinion based on well known and published issues with lightweight rigid cones.

I agree with Shadorne that the problem is most likely in the speakers. It may be caused by the metal cone (about which he knows more than I do), it may be a radiation patten discontinuity in the crossover region (my theory), it may be inadequate crossover design (an easy catch-all category), or it may be all of the above.

Speakers have a harder task than electronics, and there's more that can (and generally does) go wrong there as compared to the rest of the chain.

Duke

Wow. I tend to think that the harshness or the shrillness is the actual sound that was captured in the performance or in that recording process. Not all recorded music is soothing or smooth. An unwelcome quality of sound is appropriate depending upon the listener I would imagine. Having a solid state amplifier at 15 watts per channel with 2-way bookshelf speakers on stands in a similarly small listening room I too experience "harsh, shrill treble" at times but it appears to be more of a source problem than a system failure. Some CD recordings of the same music on different CD's sound better than others. Some CD's just sound bad no matter where you play them. Saying that, I do check connections when I hear unexpected harshness and will use a contact cleaner every few months (Kontakt) on cables and speaker connections and on AC plugs as well. This appears to smooth the contact prone harshness. I also clean the CD's when necessary and some shrillness or harshness does go away on some discs. I agree with other responses that suggest speakers have a lot to do with what you will actually hear especially in two-way configurations with a cross over and how efficient those speakers are with that particular amplifier. I would take that CD with the objectionable violin passage to my local stereo dealer and hear it on their house McIntosh and Martin Logan system and compare it to what I've got. It might be just as shrill. Or, I would purchase the same CD and see if the newer recording sounds better than the older, harsher CD. That fix is pretty cheap compared to other options. Just a thought.

also, your md 308 is no harsh amp.

Thanks to all,
I will be speaking with John Strohbeen at Walsh Ohm this week. Maybe he can put me back in the concert hall, so to speak.