Review: Rogue Audio Zeus Tube amp

Category: Amplifiers


I thought long and hard about switching from the Innersound ESL amp to a tube amp to drive the electrostatic panels on my Innersound Eros. Apart from the ESL, I had owned nothing but tube electronics for many years. There was no doubt that the Eros were in the system for good. The doubts arose from the difficult impedance load presented to an amp by the panels. I then had the opportunity to borrow a pair of VTL MB-150 monoblocks for a couple of weeks. After extensive listening, I determined two things: 1) these particular amps were not for me, and 2) a well-designed, higher output tube amp was going to provide the last bit of harmonic integrity that I found missing from the ESL. The search was on.
I had owned a pair of Rogue M-120 monos some years back, and was impressed both by their ability to provide most of what I consider most important in music reproduction and by their price/performance ratio. Now, I was using those amps prior to the existence of the first Magnum upgrade, not to mention further improvements over the years. The Rogue Zeus is Mark O’Brien’s statement product. I managed to hear one on a system very unlike my own and was extremely impressed. That amp was driving Meadowlark Herons, which feature extraordinarily benign loads, however. How would they do on the ‘stats? After several discussions with Mark (a very nice, helpful guy, by the way), I placed an order for a Zeus, and subsequently spent the following two weeks thinking “what the hell am I going to do if it doesn’t work out”? You see, this amp weighs 200 pounds. The photos on the Rogue website hardly hint at the sheer size of the thing – and my listening room is up a long narrow flight of stairs. OK, the amp arrives and I hire one of the local construction guys to help me carry it to the room. ESL out, Zeus in.

My first impressions were very positive. Playing a wide range of music, I knew that I had found that midrange magic again. Highs displayed a trace of harshness, but Mark O’Brien had warned me that break in would take 50-100 hours. The harshness was greatly diminished after 10 hours or so, and disappeared entirely after 20. One characteristic that really stands out is the lack of noise. This has to be the quietest tube amp I have ever heard. One of my favorite recordings for testing background ‘blackness’ (amongst other things) is The Sorcerer’s Apprentice on Mephisto and Co. (Reference Recordings CD). The openings notes appear out of nowhere and die away very quickly. Noisy gear absolutely ruins the illusion. The Zeus reproduced the passage perfectly.

I should explain at this point that, under ordinary circumstances, the Eros’ transmission line woofer is driven by its own amp, with an active crossover providing the split between woofer and ‘stats. However, the amp/crossover also has the capability of bypassing the internal amplifier in favor of an external unit. I had not yet sold the ESL amp, and so was able to use the Zeus for driving both the bass (with the ESL handling the panels) and the electrostatics, which of course was intended to be the final configuration. In this way, I was able to evaluate the characteristics of the amp over the full range – just not all at once.

On to the music, bass side first. I’ll not attempt to list all of the music used to evaluate the amp’s performance, but will list those that, in my opinion, provide a real test. The Four Great Toccatas and Fugues (Sony Classical SACD) is a wonderful disk for low end power and pitch definition and also for soundstaging. One sentence sums it up – the Zeus displays better control in the bass than any tube amp I have ever heard, bar none. It straddles the fine line between the overly tight presentation characteristic of many SS amps, and the loose, wooly bass that was one of the hallmarks of tube gear for many, many years. The latter has absolutely been vastly improved in newer gear, but personally the Zeus simply set the bar higher in this regard. Having said that, the Eros’ own bass amp is exemplary, so any thoughts of two Zeus amps were quickly forgotten. I am passing this along largely because I know that the vast majority of readers of this review will not be in my situation (i.e. will be driving their speakers full range with a single amp). The Power of the Orchestra (Chesky LP – why, oh why did Chesky abandon vinyl???) provides a real test of the testicular capacity of an amp. During several passages in ‘Pictures at an Exhibition’, there are a series of tremendous bass drum thwacks with an initially sharp transients and slower decays. The Zeus came up trumps on this one, reproducing said drum beautifully – and as you hear it live in a good hall, I might add. It did run barely run out of steam in triode mode and had no problems whatever in ultralinear mode. As a rule, I preferred ultralinear for bass reproduction under all circumstances anyway. This LP, as reproduced by the Zeus, also displays a huge 3D soundstage, while individual instruments – or groups of instruments – occupy their proper respective positions. Wonderful!

The rest of this review will refer to the Zeus in its primary role of driving the ‘stat panels, usually in triode mode, which I had a slight preference for over ultralinear mode. I should emphasize the word ‘slight’, and the ability to switch between the two has been extremely useful and quite instructive. Where to start? Female voice, maybe? Alison Krauss and Union Station Live (Rounder SACD) – oh my god, this is gorgeous. ‘When You Say Nothing at All’ is enough to make you cry. This is the sort of recording that shows the Eros and its associated gear at their very best. Lots of transient information, beautiful harmonies, and complex instrument interplay. The Zeus subjectively sounds every bit as fast as the ESL, while providing the midrange magic of tubes. The Eros is extremely flat and extended on the high end, so any deficiencies here are mercilessly revealed. The Zeus came through with flying colors, with no trace of harshness. Bill Evans’ Sunday at the Village Vanguard (Analogue Productions LP) is a great example of beautifully recorded jazz piano. Personally, I consider the piano to be just about the hardest instrument to reproduce realistically. Here the microphone placement was just about perfect. The Zeus catches the timbre of Evans’ piano near perfectly, while providing a holographic representation of the instrument itself. The self-titled Nickel Creek (Sugar Hill CD) showcases a trio of young, extremely talented bluegrass artists. Chris Thile’s mandolin provides a great test of transient capability on ‘Ode to a Butterfly’. Instrument sizes are exactly right, something I had not heard previously with this reference disk.

Needless to say, I am absolutely thrilled with the Rogue Zeus. The one caveat, of course, is that I cannot use the amp full range due to my speaker setup. I hope, though, that I have given you a sufficient flavor of this fine piece of gear to at least pique your interest. Best part of all – I don’t have to carry it down the stairs and re-crate it!

Associated gear
VPI Aries
JMW Memorial 10.5
Bob Graham-modified Transfiguration Temper
Aesthetix Janus
Music Hall Maverick, 1+ Modification
Innersound Eros Mk 3.5
TG Audio and Acoustic Zen cables

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