Regarding Jazzy tones,
I've had problems too... I've used several tube amps, an Acoustic Image amp, and my Axe-FX ultra w/ multiple speaker cabinets.
Then I figured this out:
1. Tone is in the hands primarily (even w/ jazz)
2. A lot of famous jazz guitarists then and now use off-the-shelf music store amps (various polytone amps, roland cubes, fender tube amps), so what is their secret??
3. A lot of the recordings we are basing our experiences from are from bad quality recordings or from live shows where the guys are using rented equipment, pa system sucks, OR you are listening to too many youtube videos (guilty). (For example, that K Rosenwinkel youtube link is a very low quality recording.... so any crispness that may be on the cd is missing... I'm listening from my Adam A7 monitors fed from my M-Audio FTU and I can tell a lot of definition is missing...maybe in the studio his amp was harsh and the sound guy rolled off the highs?)
4. The pick shape and MATERIAL will define your sound more than you think. A while back I ordered about 20 different picks to bring my pick collection to about 50 different picks. I was looking for the best sounding pick. I tried the big stubby in grey (nylon?) and in purple (plastic?) and the tone was completely different even though size and shape were same. Then I tried the 205/208 line, also by Jim Dunlop...what I huge difference.... (also picking angle.... a huge part of Benson's sound is the flat, 90 degree angle he holds the pick...it's really not the way most guitarists would do it, but it gives him a fat, juicy, even sound)
5. Strings.... ever try tomastik infeld? Chromes are great, but the Tomastiks sound 20% better... not sure how, but they really do make your tone better.
6. The guitar.... don't get me started.... brand, model, size, shape, age, tone wood, even the neck wood..., fret material, pickup brand, blah, blah, blah.... Have you ever listened to the Joe pass Virtuoso recordings? I was analyzing them one day and realized something: his tone isn't really all that fat and juicy.... and his picking noise can be annoying.... but the feel he had and the notes he chose is what gave him that sweet sound... the hands....
7. Tone knob.... if you have one, do a pat metheny and roll it all the way off..... or do that with your amp settings.... yes, you'll lose clarity, but you'll sound jazzier.....maybe.
I honestly think that for jazz, the amp is one of the less important considerations for a good jazz tone.