World Premiere Review!Rogue Audio Hera IIStereo Tube Preamplifier

Sophisticated Design, Sonic Transparency

by John Gatski

I give a lot of credit to Mark O'Brien, founder, president and lead designer for Rogue Audio. Since the company’s startup in the mid-1990s, he has stuck to his made-in-USA tube audio vision, designing and manufacturing audiophile products from his small-town Pennsylvania factory.

From the inaugural 12AU7-based Model 66 Rogue preamp (still holds up today) to the M-Series monoblocks and the mammoth-powered 16-tube Zeus stereo amp, all have been well above average to stellar in their performance — even though they are not that expensive versus some of the high-brow competition.

In recent years, Rogue has been naming its products after Greek mythology characters: Metis, Zeus and Hera, offering a variety of designs: integrateds, mono amps and even a phono preamp. The original Hera hit the market in 2006, but O’Brien was not satisfied. He decided to go as high-end as he could, but staying under $10,000. And I must say, Mr. O'Brien and team have designed a dandy audiophile preamp. It is one of the best-sounding preamps I have ever heard — tube or solid state.

Features

Retail priced at $7,495, the Hera II (named after Zeus’ wife in Greek mythology) utilizes am innovative and proprietary circuit with eight of the Russian military’s 6H30P tubes in a balanced design. Design highlights include the ultra-linear spec, Russian-made 6H30P tube, and all functional switching is done via heavy-duty, silver switches — rather than being routed through a silicon chip. Premium-quality capacitors and resistors are used throughout the signal path. Rogue President/Designer Mark O'Brien said the Hera II’s transparency is the result of its sophisticated signal path design, coupled with high-quality parts. “The Hera II uses four of the 6H30P super tubes per channel in a paralleled, mu-follower arrangement,” O'Brien explained. “This circuit provides a low-output impedance — along with a high level of power supply noise rejection.” He said the Hera II was designed with several improvements over the original Hera. “The motorized TKD, continuous potentiometer replaces the stepped-attenuator contained in the original Hera design,” O'Brien said. “And all coupling capacitors are German Mundorf ‘M-Cap Supreme,’ and Dale Vishay audio path resistors are used throughout.”

O'Brien said he squeezed more performance from a redesigned power supply with additional storage and a pi-filter arrangement of capacitors with a large inductor — rather than the capacitor/resistor network of the first-generation Hera.

O'Brien said a few other design tweaks also increases the audiophile utility of the preamplifier, including a unity-gain home theater bypass, 12V-trigger, phase invert button, and a channel balance potentiometer that is completely out of the audio path when switched out. The Hera II’s bypass mode is automatic when not powered up, so it can be left off and still pass audio — perhaps for movie playing.

The two-module chassis (one for the audio section; the other for the power supply) provides the electrical isolation necessary for the preamp's low noise floor. The unity is sturdily built and quite attractive — with its signature Rogue Audio silver and black finish.

On pop and rock music, the “warm and plump” tube preamp stereotype is nonexistent in the Hera II. Fast transients, quick percussive, tight bass and ultra accurate midrange tones are often associated with solid state, yet there they were — emanating out of the Rogue Hera II with disc after disc.

The Hera II’s main module ergonomics include a plethora of front panel controls including four-input selector rotary switch, tape monitor button, processor button, gain switch (to match various amp gain structures), bypass switch, phase invert switch, balance, balance active/inactive switch, mono button and volume control.

The back panel includes four sets of gold-sputtered RCA jacks to allow input for: phono (from an external preamp), CD, tuner and an Aux. 1. The Hera also sports a tape loop, unity-gain output for passing on the line-level signal to another preamp or amp, two pairs of RCA outputs and two pairs of balanced XLR stereo outputs. There is one pair of balanced inputs.

The power supply chassis, on which the top chassis is perched, contains the front-panel power switch. The power supply back panel contains three output cables that connect to the main chassis and the IEC connector for the power cable.

Setup

I auditioned the Hera II through a number of amplifiers including a Pass Labs X350.5, Pass Labs XA30.5, Bryston 14B SST, and a new Macintosh MC275. Other preamps I had on hand for comparison, included the reference Coda/Legacy solid-state high-current preamp, the 6SN7-tube Rogue Model 99 Magnum (with phono preamp), and an Audio-by-Van Alstine FET Valve.

Sources included a Lexicon BD-30 universal player, Oppo BDP-83SE universal player, Esoteric DV-50 universal player, Sony SCD-5400ES SACD player, Yamaha DVD2300 MKII universal player and a Rotel RP-955 turntable with an Audio-Technica 150MLX MM cartridge. I also played a number of my own high-resolution (24-bit/96 kHz) acoustic guitar and jazz guitar recordings from a TASCAM DVRA-1000HD recorder/player. Audio also was routed through DAC separates: Benchmark DAC1 Pre, Lavry DA10, Bryston BDA1 and Mytek Digital 24/96.

All sources, preamps and amps were linked to the power outlets using Essential Sound ESP Pro power cords. The sources were connected to the Rogue Hera II with Alpha-Core solid-silver unbalanced and balanced interconnects.

I listened through various speakers during the course of the evaluation: the Legacy Focus 20/20s, Legacy Studio HDs, Westlake LC8.1s and Lipinski L505s The speakers were connected to the amps using 6 ft. Alpha-Core solid-silver cables. The Westlakes, Legacy Studio HDs and Lipinski L505s were mounted on Apollo speaker stands.

The Rogue Hera II is not warm sounding in the veiled sense but is super smooth at high volume — without loss of detail. It is an incredible balancing act, but the Hera II pulls it off admirably.

After a three day “burn in,” I put the Hera through its paces. From the start, I was impressed with its ergonomic ease and build quality within the two chassis. Every control, the cabinet, the connectors and the full-featured remote revealed its high quality pedigree.

First up was the DMP SACD Steve Davis — Quality of Your Silence, which features exquisite DSD direct recording of various jazz cuts that include detailed percussion, saxophone, guitar, bass and Steinway grand piano.

I have listened to this recording through numerous preamps, and I must say that it has never sounded better than on the Hera II. Live-like resolution with incredible detail and dimension on the drum cymbals and piano. The imaging is uncannily real with instruments placed deep and wide within the mix. Just about perfect. And the Pass X350.5 was a willing partner in this positive audio exercise (I wish I had the Rogue Zeus amp for the Hera II review, but one was not available).

For classical music, I played The Frye Street Quartet — Haydn String Quartets Op. 9, no. 4 and Op. 77, No. 2 — a well-recorded chamber music SACD. Again, I was impressed by how well the liveness of the recording was relayed by this preamp. The Legacy Focus speakers showcased the Hera II’s stereo spread as if it were a concert hall. No exaggerating — just a simple, accurate relay of what what was captured through the high-resolution recording, including the rich harmonics and overtones of the cello and violins.

As I am a big fan of nylon-string guitar recorded in high-resolution, I played the Gene Bertoncini — Body and Soul SACD. This live-to-DSD stereo recording showcases deep subtleties in the complex sound of a classical guitar, (reverb detail, etc.). With the Rogue, they were were spot on. As a guitar player, it is nice to hear a guitar reproduced in its full dynamics, as it does through the Hera II. And with a top-tier audiophile system, the six-string’s sound maintains its delicate balance without blurring — at almost any volume level.

On pop and rock music, the “warm and plump” tube preamp stereotype is nonexistent in the Hera II. Fast transients, quick percussive, tight bass and ultra accurate midrange tones are often associated with solid state, yet there they were — emanating out of the Rogue Hera II with disc after disc.

Case in point, the Allman Brothers — Live at Fillmore East SACD. The live ambiance, the open sheen of the drum cymbals, and, of course, Duane Allman and Dickey Betts’ intricate guitar interplay and Gregg Allman’s organic Hammond organ, all came through as detailed as any high-caliber audiophile solid state pre I have heard.

Listening to the Elton John — Captain Fantastic and The Brown Dirt Cowboy SACD further convinced me of the Hera II’s mastery of pop music. The backing vocals on “Someone Saved My Life Tonight” are layered intricately, but clearly separated, in the multitrack mix. With revealing components, such as the Rogue, you can hear those separated layers; this is what it sounds like when the professional engineers are doing their monitor mixes.

I am a big fan of classic country music — with its combination of electric and acoustic instruments, drums and piano. I listened to numerous CDs via the Hera II, including Kelly Willis, Dwight Yoakum, Ricky Skaggs, and Dale Watson.

If you play in the high-price audio world, and want a transparent analog gain device with plenty of connectivity, the Rogue Audio is about as state-of-the-art as you will find. Sure you can always spend more money, but will it sound better than the Hera II? Not likely.

For example, the richness of the pedal steel guitar on Ricky Skaggs — Highways and Heartaches and the harmonics of a well mic’d fiddle from cuts out of Dwight Yoakum’s CD boxed set peaked my sonic attention. Also, the fevered, twang picking of Dale Watson’s Telecaster on his The Truckin' Sessions CD really stood out. The Hera II reproduced these cuts as good as 16-bit can deliver. (We need more high-res remasters and fresh recordings of classic country to hear even more detail).

Although the Hera II does not come with an internal phono preamp, I did sample some vinyl via it and the Model 99’s tube phono stage. I made a link by plugging Alpha-Core solid silver cables from the Model 99’s tape-out to the Hera II’s phono line-in.

I listened to a number of my prized, direct-to-disc LPs via the Hera II, plus some recent jazz LPs, including Wes Montgomery — Full House, a well-regarded live recording from 1963. Obviously, the phono pre signature was pure Model 99, but the Hera II’s more open and detailed gain stage allowed more of the phono pre to emerge. The Rotel RP-955 is a modest player, but with the A-T cartridge, it really comes alive. Wes Montgomery’s thumb-picked Gibson L5CES guitar tones were rich and vibrant with a well-balanced stereo image; the drums were pure 1960s live jazz. It is one of my favorite LPs, and I attribute the “wow” factor to the Hera II’s transparency.

Just because the Hera II nails the solid-state transparency attributes, it does not mean it exhibits any of the sonic negatives of silicon design. Sharp, sometimes overpenetrating treble and harshness at loud levels are not exhibited from this preamp in the slightest. The Rogue Hera II is not warm sounding in the veiled sense but is super smooth at high volume — without loss of detail. It is an incredible balancing act, but the Hera II pulls it off admirably.

I found no faults with the Rogue Audio Hera II. It takes quite a bit space in a rack if you stack the pre on the power supply. Make sure you leave a couple of inches of space to allow for ventilation. All those tubes generate some heat.

The verdict

If you play in the high-price audio world, and want a transparent analog gain device with plenty of connectivity, the Rogue Audio is about as state-of-the-art as you will find. Sure you can always spend more money, but will it sound better than the Hera II? Not likely. Try this preamp; you'll love it. Highly recommended and totally deserving of the EAN Stellar Sound Award! For more info go to www.rogueaudio.com.