Zesto Audio Andros Téssera Phonostage

Quadruple Your Input

Equipment report
Zesto Audio Andros Téssera
Zesto Audio Andros Téssera Phonostage

The Andros Téssera power supply chassis has a single power off/standby switch and an LED indicator for status that is controlled by the main unit’s on/off power switch. The phonostage draws 52 watts when on and 7 watts in standby mode. If the Andros Téssera power supply LED is not illuminated, the power-off/standby switch is in the “off” position or the unit is unplugged from AC power (under normal circumstances). The rear of the power supply has three fuse access points and a 15-amp IEC connector for AC power. There is also a power chassis connector for the supplied 3-meter umbilical cord that connects the two and supplies DC voltage from internal high-quality linear-regulated power supplies (250Vdc/12Vdc/12Vdc) to the main unit. Zesto Audio suggests this power supply should be placed away from the main phonostage (or possibly any other sensitive component in the signal chain) to keep the noise level as low as possible—that’s why it has a 3-meter cable so the user can place it farther away if necessary.

Some additional features of the Andros Téssera include passive-filtered RIAA equalization that is flat within +/-0.5dB, a noise figure at -90dBu below the maximum +8V output level, polypropylene capacitors, and 1% metal-film resistors throughout, all tube circuity with no solid-state components in the signal path, lowest part count possible for less component influence on sonics and increased reliability, and a 16-gauge zinc-plated steel enclosure. Each unit is hand built, with 50 hours of factory burn-in and a 2-year warranty (6 months on vacuum tubes).

The Andros Téssera received music signals from a Basis Audio Debut Vacuum ’table for most of the critical listening using three ’arms (Basis Audio SuperArm 9, Basis Audio Vector IV, and Graham Phantom III) and four different cartridges (Lyra Atlas, Ortofon Windfeld Ti, Hana SL, and van den Hul Colibri XGP). All four input connections were used at varying times throughout the evaluation process. I used the moving-magnet inputs with external step-up transformers because the only cartridges available were the low-output moving coils mentioned above. To test an unlikely low-output moving-coil cartridge scenario without the external step-up transformer, the Lyra Atlas was briefly connected, for functionality purposes, to the mm input with its highest gain setting (50dB) and it worked (very quietly, I might add) while only requiring the preamp volume to be increased (10–20dB) to compensate.

Under all conditions the contrasting characteristics between these cartridges were apparent: the Hana SL’s pure high-frequency tracing and fundamentally good baseline sound, the Windfeld Ti’s solid coherency, the Colibri XGP’s expressive presence region and smoothness, and the Atlas’ command of nearly everything.

The baseline sound of the Andros Téssera is full-bodied and composed. Everything stays in place, solidly rooted in location, and is presented with a sense of warmth. The sound created by this phonostage maintains dynamic development and much of the note’s decay when called for, but is slightly softer on the start than other configurations. Without favoring one over the other, all music genres seem to be fairly evenly represented.

Recently, I’ve listened to Diana Krall’s Turn Up The Quiet to enjoy her vocals and a cast of first-class jazz musicians. With the Andros Téssera in place, the music is full-bodied, warm, and rich with a calm that washes over the performance. Krall’s vocals favored slightly more throat and chest than mouth, while her piano playing had a solid heft about each key strike. Dynamic intensity of her vocals maintained the soft-to-loud transitions that are part of this recording. While the sound had reduced impact on the initial transients, the meat around the musical note continued to develop. The same appeared to happen with the upright bass playing of McBride or Clayton Jr. and with Jeff Hamilton’s percussion—a slightly softer attack but fully evolved tone and decay afterwards.

On simpler jazz recordings like Chet Baker’s Chet album, the Andros Téssera continued the trend of warm rich sound. On “Alone Together” Chet’s trumpet sounded big and rich and immediate—in and around the left speaker—while the sound from the echo chamber filled all of the right side of the soundstage like two distinct scenes from the same source. Cymbals were sweet and blended well with the accompanying piano in this composition. The upright bass was slightly soft but each note change was distinguishable throughout the track. Pepper Adams’ baritone sax had room-filling body (less reed sound) and intensity. Similarly, Herbie Mann’s flute was warm and smooth. With the Andros Téssera, one could get lost in this simple but beautiful music until the side of the LP was completed.