Esoteric S-05

Today we discuss the Esoteric S-05 a power amp for fine palates. Class A, impeccable construction and much more you will find just below.

Esoteric S-05 30W Class A power amp

TEAC Corporation was founded in 1953 and has spanned all eras of Hi-Fi, from vinyl through cassette recorders (the manufacturer was an excellence in tape-decks) to CDs and Super Audio CDs in the digital age, and then modern-day streaming. At the beginning of the CD era under the TEAC brand name debuted a number of players featuring the revolutionary VRDS transport, some of you may remember the VRDS-20 and VRDS25

Esoteric was born shortly thereafter, as a Hi-End branch in the middle of the transition, straddling vinyl and CD, and of course immediately adopted VRDS, which-unique in the world-literally crushed the record using a platter as large as the CD itself. It immediately set a standard that is unmatched to this day, not least because Teac Corporation has never allowed third parties to use the VRDS mechanism. After numerous refinements, the latest evolution is called VRDS ATLAS, which moreover equips the K-01XD SE model we tested, and joins two others, VRDS-NEO and VRDS-NEO VMK-5 that equip the gradually lesser models in the range. Along with the players, Esoteric since the early 2000s has started to produce electronics, pre and power amplifiers from the Grandioso series first and then some other models of integrated amplifiers and pre/finals.

The class of "A"

The Esoteric S-05 is not Esoteric’s first class-A power amp; it predates the A-03 of 2010 and probably will not be the last. At a time when Class D and limited power consumption are all the rage, such a product sounds like a bold counter-trend: the S-05 offers a total power output of 60 watts into 8 ohms and draws 235W. But Hi Fi enthusiasts know well that a class-A power amp sounds different. Due, certainly, to its inherently lower distortion, which, however, is paid for by power consumption in the absence of a signal even slightly higher than at maximum power output. After a few minutes of turning on a class A power amp the temperature rises, and not by a little. In the case of this S-05 being the enclosure in the way the heat is less noticeable, in the case of exposed fins-the Musical Fidelity A1 for example-not infrequently the heat can reach in the summer months as high as 70° (!!!!). S-05 therefore, for certain, needs air, lest the thermal protectors intervene by removing the power supply.

Esoteric S-05 has the “classic” power of a class A amplifier, 30W into 8 ohms. It is that right size, for which there is no need for overly large allotments, stellar absorption, but most importantly, at least in the experience of the writers, you get the best balance between power, absorption and manageability. Indeed, you have to imagine that higher powers demand exponentially larger radiators, not least so that the fin does not get too hot, which would otherwise become unmanageable. Even 80° for semiconductors would be a much more than tolerable temperature, the problem is that you would inevitably get burned, and so to avoid this the dissipating surface area must necessarily increase.

Esoteric S-05: a versatile finale

Esoteric S-05 has totally symmetrical configuration, and has, therefore, both balanced and unbalanced inputs, needless to say that given its nature the best thing would be to adopt an equally balanced DAC/PRE or preamplifier. On the front panel only a switch and an LED, while on the rear panel, in addition to the usual XLR and RCA inputs, there is an additional XLR but male that is used to connect the power amp to other Esoteric electronics via the proprietary ESL-A current standard.

Then there is a pass-through trigger input and input, XLR, ESL-A and RCA input selector, mode selector, i.e., stereo, bridged mono offering a claimed power of 120W/8Ω or bi-amp. For the latter the inputs are put in parallel but only the Left input should be used, in the case of bridged connection the Right should be used instead. Automatic power-off control, and output binding posts complete the equipment. Aesthetics are typical of the current Japanese manufacturer’s, aluminum exterior, floating lid, thick metal chassis, decoupled steel feet.

Internal construction

Esoteric S-05 is among the few products not to have a toroidal transformer, but rather a traditional one, albeit shielded through a strong copper band, so as not to leak flux. Its power rating is 940VA, a truly remarkable figure, immediately after it the configuration is completely dual-mono, starting then with the rectification, done with extra-fast diodes each with its own fin.

4 the 10,000-µF capacitors per channel wired directly to the end sections, equipped with 6 mosfets per side and with a power distribution made with copper rods soldered to the printed circuit board. The configuration is balanced and therefore this type of connection is recommended, but on the large printed circuit board immediately behind the rear panel only also housed unbalancers, so as to make S-05 compatible with any source. Also on the same printed circuit board is the control logic, which oversees power on and protection, essential in a “high temperature” product such as this.

Listening to Esoteric S-05

S-05 is the typical class-A amplifier. Beautiful, delicate, enveloping, warm. We tried it both in the system in Room 1, so with the Kaya 90 and Playback source and with the S12, the smaller ones from Vivid’s house, in both situations S-05 was able to dominate the scene thanks to an absolutely unique way of delivering the sound message. After all, class-A amplifications, in general, have their own sound, their own “signature,” of whatever brand and power rating they are. But no doubt the low-power products are even more magical than the more muscular ones. But do not believe that 30W in class A is little, far from it, it is enough in practically all situations, even those where you would never believe. Maybe it’s the “good” distortion, maybe it’s that always caressing way of dealing with every nuance, but S-05 really bewitched us. The purchase price is certainly not cheap, but neither is it excessive, especially if you take into account the current quotations of Hi-End products, and this S-05 undoubtedly belongs to that segment

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