Most beneficial change .

I agree with the zu recommendation. However, I recommend borrowing another good cd player first. And borrow a turntable if you can. I don't imagine the kt88 tube to be the issue.

Also, Prat roughly refers to speed of transient attack and clarity of rythm at any tempo.

IMHO, of course, the things that cause a boring system: 1) boring music, 2) slow transients and/or slurred timing, 3) and veiled harmonics.

If 2 and 3 are excellent, you will have natural timbre, dynamics, PRAT, and detail. If they are not well done, no big dynamic swings, tempo, big volume, slam, punch, room treatments, wire, stones or tweaks will replicate music well.

Generally, harmonics mean the overtones associated with sounds. For example, if I strike an "a" key on the piano and the string is tuned to vibrate at 440 cycles per second, the sound that predominantly comes out of the piano will be "a" at 440. However, the piano string itself will give off other sound waves in addition to those at 440 cycles per second. For example it may give off additional waves at 880 (one octave above) and 1300 and 1720 and more. These are harmonic overtones and most instruments project them along with the predominant sound of each note.

Additionally, when I strike the "a" key, the piano box itself and the other strings in the piano will vibrate to some extent from the energy released when striking the "a". These extra sounds give all instruments unique character. My explanation is imprecise and any physicist is welcome to chime in here.

When harmonics and these extra sympathetic tones cannot be heard, most instruments will sound boring. When they cannot be heard or they are squashed, I call it "veiled". One can have a system that while it projects the "a" at 440 very cleanly, it sounds "dry" or lifeless, because the harmonics and other extra (ambient) sounds are missing.

In my experience, tube gear does best at reproducing harmonics and ambient sounds and the less feedback used, the better. At this stage in my hobby, I'm unlikely to consider any amp with more than about 1 to 2 db of negative feedback (and zero is preferred) and I have never heard a solid state amp that really pleased me (not saying it does not exist).

So, what do "veiled" harmonics sound like? Well, put the lid down on the piano, throw some heavy blankets on top and you get the idea. You will still hear the "a", but a lot of its overtones and the piano's ambient sounds will be damped or killed. Or, compare the sound of an electric fender rhodes piano to a real piano, hence the reason for the wane in popularity of the fender piano.

Jylee, what is your evidence that tube amps "add" additional 2nd and 3rd harmonics?

I have heard that tube amps emphasize even order harmonics and that solid state amps emphasize odd order harmonics. I've not heard that either embellishes the music by creating them where they are absent from a recording. It may be true, I just have not heard it put that way and I'm curious as to the source.

Where is Ralph when you need him?

In the two test samples, it appears the tube amp adds predominantly second or even order harmonic and the solid state amp adds odd order harmonic (at a comparatively lower level (amplitude?)). It may be worth noting that the authors complained of significant hum in the tube amps tested, which could affect the output, but I'm ready to accept that both tube and solid state amps add harmonics to the source material.

The tests were performed on a 50khz pure sine wave. I am interested in seeing the results of similar test feeding the complex waves of a real instrument, say the strike of an "a" on the piano. Is that test data available comparing a tube amp to a solid state amp?