John gives good advice. Having lived with Avanti & heard & helped set up quite a few, I'll try to set some ground rules & maybe also explain where John 1 is coming from.
General comments: FAST speakers; easy to make them chirp, but TRICKY to get the last ounce out of them. The tweeter will NOT tame (roll off, etc) any harshness that's fed to it; the lower mids need current to emerge. Generally it's a VERY precise speaker. IMO, it's a phase & pitch correct speaker -- and driven correctly it WILL offer seamless, fast sound (good for jazz, that!). For these reasons,
*highly resolving AND musically inclined electronics (as per John1) are necessary.
*Fast & "neutral" (well, as far as we can get that) cables are necessary.
*So, electronics & cables are VERY important. I'd go there first. Then,
*finances permitting, top-notch source components: if not, you'll hear it (but maybe you can live w/ it for some time?).
On digital source, I'll just add that a Capitole II or similar level of performance is what you're looking at.
Using both TT & digital, the following components sounded good (this is MY experience, of course not the absolute list!)
Cables: spm ref, valhalla, bearlabs cables on speakers. Bearlabs, valhalla, purist dominus (very expensive), for IC. I found that Nordost 4fil, a good performer, was bettered by the above IC's.
Electronics: my experience with 3's & tubes is limited, so refer to John, above. I did try and enjoy:
*KR Antares (tube) driven directly, and with a CAT ultimate. *Pathos monos (hybrid) with their own pre. For tube, you might add John 1's ARC (his being the better sounding, older model).
*CAT Ult pre/Symphonic Line pre + Symphonic Line rg4 monos: probably the FASTEST system I have ever listened to.
*YBA passion pre + passion stereo (not far from the old Aleph sound -- s/what fuller & faster. The new YBA pre is better than the old aleph).
*CAT Ult. pre/Symphonic Line RG3+full PS pre + Symphonic Line Kraft 250 classA amp, both stereo & mono versions. The mono's are overkill.
The Kraft stereo/CAT combo gave the absolutely BEST sound for active line, followed closely by the YBA combo. On phono, the RG3/Kraft combo gave the best sound, again followed VERY closely by YBA.
The Symphonic Line RG4 monos combo follows. VEry good with rock & jazz
Please note that I judge by classical when evaluating equip. So my opinion is... tainted AND limited by the few amps I've tried on Avanti 3's.