SST Thoebe II Preamplifier and Son of Ampzilla II Power Amplifier

Chips off the (Good) Ol’ Blocks

Equipment report
Solid-state power amplifiers,
Solid-state preamplifiers
SST Son of Ampzilla II,
SST Thoebe II
SST Thoebe II Preamplifier and Son of Ampzilla II Power Amplifier

Back in the day (and the day I’m talking about is close to forty years ago), the great designer James Bongiorno attracted a lot of attention with his crazily-named designs—not to mention his wacky hats, suits, press releases, and letters to audio journals. These designs also pricked up a lot of ears for just how good solid-state electronics could sound. I refer to his Ampzilla and Son of Ampzilla amplifiers, his Thaedra and Thoebe preamplifiers—surely only Bongiorno could link invocations of trashy Japanese disaster movies and ancient Greece—which he marketed via the company he founded, Great American Sound or GAS (I don’t even want to speculate what was on his mind when he came up with this, but surely the scatological implications can’t have been accidental). Bad health deprived him and high-end audio of a couple of decades of what would have been his prime as a designer. In the aughts he started up a new company, called Spread Spectrum Technologies, and 13 years before his death in 2013, he was able to introduce fully updated versions of Ampzilla, renamed Ampzilla 2000, and a new preamplifier he christened Ambrosia, named for the food of the gods in ancient Greece or, alternatively, a food that conferred immortality. True to himself to the end, the man was incapable of understatement. I was privileged to review—rave review, I should add—these two products in 2012 (Issue 219) and even more privileged to get to know James for a short while. Although we never met in person, we talked several times by phone. In my view those products are as good as anything you can buy—and fully worthy of becoming classics.

At that time, James had already begun new versions of the Son of Ampzilla and Thoebe preamplifier, both monikers retained only with “II” suffixes added. The name Thoebe brought back some wonderful memories, because it was my favorite of all the preamplifiers I owned prior to Dick Schoener’s Nova. And I liked the Thoebe much better when it came to functionality because it wasn’t minimalist. James believed control units should control and so included bass, treble, and balance controls, stereo/mono switching, and independent tape loops with cross-recording and full monitoring. The Thoebe II perpetuates this tradition, losing only the tape loops (does anybody actually tape anything any longer?).

But I’m getting ahead of myself. While the new products originated with Bongiorno, the cancer he’d battled for over two decades claimed him before the designs were in any sense functional. Bongiorno’s company was acquired by Wyred4Sound, where E. J. Sarmento, the resident designer there, completed them. I choose the word carefully: completed, not finished. According to SST’s Tony Holt, the products represent about seventy percent collaboration between Bongiorno and Sarmento and thirty percent Sarmento on this own. “Son of” is surely an apposite name for the new Ampzilla amplifier because it’s a chip off the old block, beginning with a massive 20-pound toroidal power supply. The circuit is fully balanced, configured to be extremely quiet, and provides A/B switching between balanced and single-ended modes; all jacks are gold-plated. Speaker outputs are via heavy-duty binding posts. The amp is servo-controlled with isolated and fully regulated front-end voltage supplies. There is a welcome turn-on surge delay, and thermal protection shuts the amp down if presented with any condition that might damage it (this never happened while I was using it). The power output is 220Wpc into eight ohms, 350Wpc into four. At no time during my use—mostly driving Quad 2805 electrostatics, but also Harbeth’s Super HL5 Plus, and the new Falcon LS3/5a—did the amp exhibit any behavior that suggested less than consummate ease, composure, and stability. The base price is $3500.

As regular readers of mine know, I believe fervently in bass and treble controls. Bongiorno told me he liked them because “no room is perfect.” I agree, but conventional tone controls are generally speaking much too broad in their effects to be of much help in correcting room modes. But when it comes to source material, broadband tonal correction really can make an excessively bright recording listenable—and let’s face it, most recordings are a little bright owing to the proximity of the microphones—or warm up one that is bass-shy (e.g., most of the George Szell recordings for Epic and Columbia are both bright and bass-shy). Initially I wondered if the centers weren’t too high in the bass—300Hz, the low-end of the midrange—and too low in the highs—3kHz, the low-end of the high range. But slopes are so cannily chosen I was completely won over. Used with care, these controls can transform any of number of tonally unmusical recordings into pleasing and listenable experiences.

The operation and display of the balance control were initially confusing to me. I’ll explain: When the balance control is selected, on one side of the display an arrow appears and on the other side, you see a numerical indication of level. The arrow points in the direction of the channel being raised and is illuminated on that side of the display. Thus, if you’re raising the volume in the left channel, the arrow will appear on the left side of the display pointing toward the left speaker, while the numerical setting appears on the right. This makes perfect sense except that the symbol does not look particularly arrow-like, so the first time I used the balance control, I assumed that the numeric display was on the same side as the affected channel. When the volume was raised in the opposite channel I rechecked all my connections; as they were correct, I was thoroughly perplexed until I realized that that symbol was supposed to be an arrow. This sort of misunderstanding could easily have been prevented if the manual had provided some explanation; as written, it’s rather barebones for a unit of this sophistication.

On the plus side, every one of these features is accessible via the handset, which makes it my kind of remote. However, it’s not stock, but rather an optional accessory costing $175. This seems to me rather steep, but I acknowledge that it’s a very sophisticated device and impressively constructed from what feels like a solid block of aluminum.

A Class A headphone amplifier comes standard in the Thoebe, with a pair of ’phone jacks accessible via the front panel. I don’t much listen to headphones, but if you do, this should fill the bill about as well as anything you’re likely to find out there. And one feature I really appreciated is that only one of the jacks automatically mutes the main outputs—a smart feature, as you don’t necessarily always want the speakers muted when listening to headphones. Connectivity consists in three pairs of single-ended (RCA) and one pair of balanced (XLR) outputs, and four pairs of line-level RCA and one pair of XLR inputs.

The Thoebe II can also be purchased with a built-in phonostage and/or an internal DAC at an additional $500 each. The phonostage takes up one of the RCA inputs, while the DAC option adds USB, coaxial, and TosLink inputs. If purchased together, SST knocks $250 off the $1000 total. So a fully tricked-out Thoebe II with phonostage, DAC, and remote will set you back $4250. This seems to me to be very good value: like the amplifier, it worked absolutely flawlessly, was a joy to use, and in ergonomic terms struck me as about as close to perfection as you can get. If I did not already own a preamplifier that serves my needs perfectly well, the Thoebe II would be a very tempting purchase to consider (though if Sarmento is ever tempted to make a change, I would wish for a stereo/mono switch).

When it comes to the sound, these units remind me of the Ambrosia and Ampzilla 2000: the same quietness, smoothness, transparency, dynamic range, and that elusive impression of body, dimensionality, and solidity. It’s been three years since I had their more expensive brethren in the house, but I suspect that in an exacting A/B comparison, considerable concentration would be required to distinguish one pair from the other. Given their lineage and the fact that they are fully contemporary solid-state designs of great competence and sophistication, describing the sound does not invite purple prose or any other sort of colorful language, which is to say that it is neutral, transparent to the source, and in any practical sense distortion and noise-free.