Rogue Audio RP-9 Vacuum Tube Preamplifier Review

By Bob Grossman

The Rogue Audio RP-9 is the latest flagship preamplifier from the ingenious designs of the American manufacturing workshop of Mark O’Brien.  Having an interest in doing this review of the new RP-9 was a simple decision as a long-time user of the Rogue Audio RP-7.  I have been using the remarkable powerhouse Rogue Apollo Dark Amps for several years as both a sonic and output upgrade to my previously owned Rogue 180 Amplifiers that were used to run Magnepan 3.6 speakers. 

I replaced the Maggie 3.6 speakers with their 20.7 models several years ago and needed more powerful amps. I wondered if the increased musical experience of moving further up in the Rogue Amplifier line was going to be repeated with their new preamplifier by going from the RP-7 to the Rogue Audio RP-9 model. However, before proceeding and hearing the RP-9, I wondered what was going on since the RP-7 has received numerous accolades, recognition, and rewards. Could designer Mark O’Brien improve upon the noteworthy RP-7 that I have been enjoying?

I immediately shook my head in a positive way when I switched on the RP-9. I was amazed that the sound could be that much better than my RP-7, which I felt was wonderful. How is it possible that the sound of the RP-7 was improved across the board in every area?  The RP-9 has a quieter and more silent background that was deeper in the projection of space.  There were layers of sound magically appearing from further reaches and areas behind the speakers. 

The music floated in the room with a sense of being at a concert hall. Notes were spinning everywhere with the sound connected in time yet there was space and separation. Rogue Audio’s RP-9 stereo preamplifier creates a natural breath with the playing of winds, a cutting edge to the brass, a glimmer to the percussion, and jump to the beat of the sticks impacting the drumheads. The bass seemed to go lower by an octave because what was previously heard now had better definition and authority. 

The textures and tapestry of the music took on further levels of saturation and colors.  It was a mesmerizing improvement of the musical presentation and listening experiences across all the areas audiophiles hear and discuss such as depth, width, and height of the front sound stage or the speed, resolution, attack, and delay of the music presentation. 

Meet The Designer

Mark O’Brien lives near the beautiful Pocono Mountains in Broadheadsville, PA about 90 minutes north of Philadelphia where I reside across the Delaware River in South New Jersey. Unfortunately, due to 2020 / 2021 restrictions I was not able to drive to their factory to hear the RP-9 on his system. Instead, I called Mark for information. Mark said the RP-9 is identical in appearance to the RP-7 but was designed around the 6H30P tube, which necessitated an extensive redesign of the audio circuit to accept the new tube compared to the RP-7 with the 12AU7 tubes along with other power supply and parts upgrades. Initially, Mark built four boards for himself and a few friends. They found the preamp sounded so good that he decided to turn it into a product.

I decided to go with a silver finish for the RP-9 instead of the black casework of my RP-7 to aesthetically match other new components of the stereo. The metal housing is well made and finished with a heavy front faceplate, large knobs, and easy-to-set buttons for the inputs.  The top hatch easily unscrewed for a peek inside to see what was going on. There sure were a lot of power supplies, parts from Vishay, and Mundorf silver/gold oil caps. My Dad was an electronics technician back in the golden era of all-tube equipment and TVs.  I miss not being able to show him all the tube gear I use. I think he would be impressed with our new modern-era tube equipment that has much more reliability and accurate sound.

Of course, the debate rages on about the odd or even order harmonic sounds and reliability of tubes versus solid-state designs or the basic musical sounds from rolling NOS vintage tubes and newly manufactured tubes from various sources.  I have had experiences with some of the finest equipment in professional recording studios.

I enjoyed great sound for many years when I owned three different Krell preamps along with three of their big amps all through the 1990’s and into 2010.  I also got to use and hear the excellent preamp and 911 amp from Burmester when reviewing Genesis speakers. 

Eventually, tube amps showed up with other review equipment projects.  There was a remarkable sweet integrated 300B design from Allnic and the gutsy and punchy Bob Carver 180. This led me to Rogue and hearing their lineup of the tube and hybrid equipment. I found Rogue products to be very value-based performers relative to other company price points for equipment.

Building On Experience

The combination of the Rogue Apollo Amps and the RP-9 sound is like the experience and charm of sitting down to a delicious meal that is perfectly balanced from the enticing hors d’oeuvres to a fulfilling main course accompanied with a fine wine or superb Trappist Belgian Ale and finishing with an elegant dessert. The RP-9 control and contribution to the stereo are like having a personal chef cook my favorite meals that are healthy, nutritious, balanced, and enjoyable.

The combination of the RP-9 and Apollo Dark Amps always served up a terrific array of musical presentations.  It was fine regardless of the repertoire and musical style I had spinning on the VPI HW40 or Aries turntables or when listening to a CD.  I mainly listen to classical and jazz.

The Rogue equipment has the clarity, power, and speed to make electronica, trance, rock, and pop music all pleasing and involving too. The Rogue does not have a traditional warm tube sound from my Dad’s listening days and thankfully does not have any solid-state glare from the early days of transistors that my Dad also experienced and did not like. Rogue offers a wonderful integrated and complex sound that is very engaging and accurate too.

Another beneficial design Rogue offers owners is a process and plans for equipment upgrades for many of their current models for customers that wish to update their earlier purchases. These can easily be viewed on their website. The company history and design approach are explained in greater detail too along with the manuals for their products. Their Ares phono stage which I also own is an excellent performer and value at $1,995 yet they offer the nicely upgraded Magnum model at $2,795 that has a significant list of premium parts for a person that would like to further enhance the sound.

A similar path of parts refinements is offered with the Rogue 180 and Apollo amps that have the basic or dark versions.  The production labor costs are similar, but people can decide for themselves if the distinct parts and results are worth buying. Rogue does not appear to overly markup their premium product lines.  It is mostly about the parts upgrades. In a way, I think the Rogue Audio RP-9 vacuum tube stereo preamplifier is a similar performance upgrade path that leads to a greater sound than the excellent RP-7. The appearance, features, and setup are identical with both preamps. The circuit design of the RP-9 is similar too with mainly topology mods for the tubes and other power supply parts while including a beautiful new metal housing remote.

Why Vacuum Tubes Are Important

The differences between the Rogue Audio RP-9 and RP-7 are not just upgraded parts and boards but the essential tube switch.  I have only owned and heard preamplifiers that utilized the 12AU7 and 12AX7 tubes, so I did not know the sound of the 6H30P tube.  However, I am aware that several other highly regarded manufacturers use the 6H30P tube in their expensive preamplifiers. 

Mark O’Brien has designed another great preamp that is competitive in the results and price comparisons to other choices in the marketplace that utilizes the nicknamed Russian military super tube. Mark has designed a new preamplifier that rightfully offers a new level of sonic performance beyond the award-winning RP-7.  The RP-9 is quite pleasing with remarkable levels of transparency, musicality, and details at a price point that is extremely competitive with other companies that feature the 6H30P tube as part of their preamplifiers.

The Rogue Audio RP-9 exudes a beautiful and wonderful balance, presentation, and delivery of sound.  Average recordings sounded better and were now more musically engaging and listenable with greater emotional involvement.  Great recordings became excellent and had a new, higher level of realism.  The best of the best excellent recordings transcended their already superb sound and became realistic sounding as if I were at a live concert.

Putting It In Perspective

I played bassoon for the past 50 years and was always concerned about my tone and ability to blend and harmonize with the other musicians in the ensemble while still being able to project and express my own sound.  The tone must be the right balance so the beauty can be heard by the audience in the back of the auditorium.  A bigger sound and powerful projection often come at the cost of something else in the dynamic balance between the sense of loud and soft along with the sweetness of sound.  The sweetness might not be an accurate word in the typical sugary sense to describe what I hear, seek and perform. It is a balanced musical sound that enables flexibility in tone colors, voices, and saturation within the ensemble. When it’s right then I say it’s sweet!

I relate to the finest musical presentation by audio equipment from this type of perspective.  A big, loud, and thumpy system with stridency is quite the opposite of what I enjoy.  When I speak of a stereo having a musical sound it is because I am experiencing and hearing a realistic portrayal of timbre, balance, and textures of instruments and voices. Then along with the transparency and layers of sound with quick and variable dynamics, speedy and clear articulations of initiations of notes, it should also have an appropriate amount of resonance and decay with a full frequency range for all the instruments and voices.

I was at a Deutsch Gramophone Philadelphia Orchestra recording session for the Shostakovich Symphony Number 4 back in the 1990s with Myung-Whun Chung guest conducting.  This is a very demanding orchestra recording to play and makes a great demo at home. I put on a Japanese CD version and checked the sound level to be loud in the mid 80s decibel range yet not realistic to the live orchestra in the studio sound.  I slowly turned up the numbers using the new beautifully styled and crafted metal remote of the RP-9.  The RP-9 level numbers on the OLED screen can easily be seen from my listening chair.  That is another nice feature about this preamp. 

The new remote is a pleasure to hold and use.  The settings can be seen from across the room although the screen can also be turned off if a person does not want to see any lights. I got the sound past 90 dB and even had peaks during the tympani and bass drum transients to momentarily break 100dB.  Now this was the intensity and sound level I hear live when I am on stage with the Orchestra.  The RP-9 was brilliant in simply dialing up to louder levels of playing without any sensations of distortion or compression creeping into the path.  I did not want to stay at this volume for long, yet it was pleasing and rewarding to know the system could do this.

The sound and challenge of properly portraying the complexities, colorful instruments and multiple voices of Renaissance music is another favorite demo and musical test of any great system.  I have many wonderful French and German Harmonia Mundi records.  Two of my favorites are La Fete De Lane with the Rene Clemencic Consort and La Folia with Gregorio Panaigua.  These are beautiful, humorous, and creative performances that I have enjoyed for over thirty years with the use of many systems. 

Rogue Audio’s RP-9 relayed and portrayed all the noisy gags of La Folia including buzz saws, car horns, squawking balloons, engine exhausts along with the cadre of plucked and blown period Renaissance instruments.  I have a couple of versions of the Feast of Fools that I always play to celebrate the holiday festivities around New Years.  Along with the bawdy and sometimes sarcastic singing commentary of Carl Orff’s Carmina Burana, the Fools old traditional play and presentation also took great liberties with a skewed comedic and irreverent presentation.  Rene Clemencic has taken great liberties and creative license in recreating this montage of dancing and singing merriment.  My stereo has never been as enjoyable as hearing it with the combination of the RP-9 and Apollo Amps.

A God of Music

I have observed that Rogue often uses Greek mythological names for its products. I wish Mark O’Brien would consider a lovely maiden name for the RP-9 rather than a numeric title so that his other Greek mythology-inspired Apollo Amps could symbolically add one more lover to the known group of Apollo’s nine muses.  Immediately after his birth Apollo demanded a lyre and invented the paean, thus becoming the god of music. As the divine singer, he is the patron of poets, singers, and musicians.

The invention of string music is attributed to him. Plato said that the innate ability of humans to take delight in music, rhythm, and harmony is the gift of Apollo and the Muses. According to Socrates, ancient Greeks believed that Apollo is the god who directs the harmony and makes all things move together for gods and humans. The RP-9 is a new muse that has inspired the Apollo Amps to sound better.

Two Steps Closer To Heaven?

Rogue Audio’s RP-9 tubed stereo preamplifier brought increased musical joy as I listened to Miles Davis perform over a wide range of groups and eras of his extensive career starting in the late 40s.  I’ve loving hearing his records for years and find them to be constantly involving performances that have become deeper and more profound with the growth and revelations of the stereo improvements over time. The 1963 Columbia album Seven Steps To Heaven is a remarkably interesting transitional part of his career as several of his long-term sidemen had departed and Miles was forced to form a new band. 

The group of players on this record did not stick together long which is a shame since their playing is quite good and a lesser-known favorite of mine before Miles got his second great Quintet established.  The second track on this album is the tune “Seven Steps To Heaven” jointly composed by Miles and the British pianist Victor Davis that had a brief time playing with Miles. I could not help thinking that regardless of how good the Rogue Audio RP-7 sounded with the presentation of this music, the RP-9 took me a step closer to the sound in the studio.  I do not know if that is so since I wasn’t there but wiggling and tapping my feet nine times more when hearing this record is a helpful two steps forward.

Summary

The Rogue Audio RP-9 vacuum tube stereo preamplifier is magical. I was a very satisfied listener to the RP-7 for the past three years and could easily have continued. However, once I heard the differences of the RP-9, I was sold. The RP-9 is dynamic, transparent, and revealing. The soundstage took on a greater sense of depth, width, and height.  The attack and decay of notes had a greater and speedier delivery with more articulation. 

There was a greater sense of resolution and the details seemed to appear from a darker and quieter background.  I like being involved with music. I especially feel an intangible emotional response to the musical recreation and portrayal of a beautifully designed stereo that enables the recreation of performances with the distinct sounds and voices of renowned artists. The price of admission into the realm of the RP-9 is justifiable given the payoff.

Mark O’Brien of Rogue Audio and his listening friends got it right!  The 6H30P tubes have a fascinating and clear singing sound.  Mark has made the music sound Sweet. The topology and parts revisions have contributed to creating an impressive preamplifier that takes the Rogue sound another step forward of leading the heart, mind, and soul to the happiness of musical involvement. I have a greater sense of music enjoyment relative to putting up a larger expense to buy the Rogue Audio RP-9. My verdict is a definite positive endorsement.  Bravo to Mark and his accomplished crew!

Specifications

• Type: Vacuum tube stereo preamplifier
• Frequency Response: 1Hz to 170KHz (+/-1dB)
• THD: <0.1%
• Gain Line Stage: 14dB (20dB XLR)
• Rated output: 1 Volt
• Maximum output: 30 Volts
• Output Impedance: <10 Ohms
• Tube Compliment: Four 6H30P tube mu-follower design
• Ten function remote control
• OLED display (defeatable)
• Inputs:
  • Home Theater bypass/Unity gain inputs
  • Three pairs of RCA line level inputs
  • Two pairs of fully balanced XLR inputs
• Outputs:
  • One pair of fixed output
  • Two pairs of RCA variable outputs
  • Two pairs of fully balanced XLR outputs
  • Processor loop
• Heavy duty gold plated RCA inputs
• Tube based high power headphone amp
• Dimensions: 18.5″ X 4.5″ X 17″ (WxHxD)
• Weight: 30 pounds
• Warranty: Three year limited warranty (six months on tubes)
• Proudly hand crafted in the USA
• Price: $7,495.00

Company Information
Rogue Audio
P.O. Box 1076
Brodheadsville, PA 18322

Voice: (570) 992-9901
E-mail: info@rogueaudio.com 
Website: www.RogueAudio.com

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