An electrostat, direct-radiator dynamic, or horn system succeeds to the extent that it reproduces the illusion of a live performance.
Transparency varies more from speaker to speaker than from amp to amp or preamp to preamp.
Low coloration (including smooth and extended frequency response and freedom from resonances & diffraction) is crucial to good transparency.
In my opinion, much of the open and transparent presentation of a good electrostat is related to the radiation pattern. Electrostats have unusual radiation characteristics: Usually line source (emphasizes first-arrival over reverberant sound), usually relatively narrow pattern (minimizes early floor, ceiling, and sidewall reflections), and lots of relatively late-arriving energy to add richness and spaciousness (largely the result of the dipole pattern). In addition, several of the more successful manufacturers go to some effort to keep the radiation pattern reasonably uniform, which is beneficial to timbre because it preserves the spectral balance of the reverberant sound.
In my opinion a low-coloration horn system in an acoustically "live" room does many of the same things well that a good electrostat does. In my opinion it's a bit harder to get the same sort of presentation from a direct-radiator dynamic system. Direct radiator dynamics give you deeper bass and typically better imaging in a smaller package.
If you like the presentation of a good electrostat but for whatever reason neither electrostats or high-quality horns are practical for you, you might consider Maggies, Audio Artistry, Gradient Revolution (I sell these), Linkwitz Orion, and Eminent Technology. If you have the financial resources but not the space, you might consider the Acapella LaCompanella.
Duke