To digress a little, I am using an Almarro 318B with Zu Druids and the amplifier is wonderful. However, the sound from the Almarro is heavily dependent on the pre tubes. I settled with a Mullard brown base CV569 (6SL7) and a Sylvania 6SN7GTA for wonderful warmth and detail. The SED 6C33C power tubes bettered the Sovteks with a little more detail and extension.
This tube combination (by my ears and preference of course) gives the best midrange that I have ever heard out of any amp and still had delicate and revealing highs without harshness. With the wrong pre tubes, the Almarro sounded dull and blurred. Perhaps the Zu people did not have the Almarro on their list because they did not tube roll it or perhaps did not review it, as it bested the Melody I2A3 which they said is "awesome".
I owned a Cary 300SEI with Western Electric 300B tubes and the Melody I2A3 recommended by Zu, but found the Almarro 318B to sound superior overall, especially for midrange warmth and engagement. The Almarro also has delicate and revealing highs and can even rock when called upon with its measured 20 Watts of SET output. The Melody I2A3 had a tad more finese and silkyness in the highs and a little more forward soundstage. The Cary, 300SEI although very nice, suffered from a little bit of the dryness that I almost singularly seem to hear in some of the Cary equipment.
However, the Almarro won handily in overall midrange presence, giving out an immediate front row center sound with full tube 3D realism and depth. It was wonderful with vocals, instrumentals and jazz, yet still possesed engaging sweet yet detailed silky highs - and as mentioned, can play rock when called upon without being embarrassed. The Almarro should have no trouble powering Zu Essence, Sous or Omens (or Omen Definition speakers for that matter as it powered both my Druids and Tones simulataneously in an effortless fashion).