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Positive Feedback ISSUE 33
september/october 2007


harmonic technology

Pro-9 Reference External Bi-wire speaker cables

as reviewed by Robert H. Levi






Avalon Eidolon and REL Stadium III subwoofer.

E.A.R. 324 phono preamplifier, E.A.R. 890 amplifiers (ran as monos), NuForce Reference 9 SE V2 amplifiers, E.A.R. 912 preamplifier, and an E.A.R. 834L Tube Line Stage.

VPI Scout/JMW 9 tonearm, VPI SDS Controller, ZYX R-1000 Airy 3-XSB phono cartridge, E.A.R. Acute CD player, ModWright Sony 9100 Player with tube power supply, ModWright Sony 9100ES with Signature Truth Modifications, Mod/Bybee Filters and Revelation Cryo Silver Umbilical. Alesis Masterlink 24/96 Recorder/Playback Deck, and the Benchmark DAC 1 revised. Grado Statement Phono Cartridge. Pioneer DVL 919 LD/DVD Player, and a Marantz DV8400 DVD/SACD/CD player. Magnum Dynalab MD-108 Reference Tuner, Marantz 10B FM Tuner, Day Sequerra Reference FM1 Tuner, and Scott 350B FM Stereo Tuner, AQ 7500 FM Antenna, Stax 7t Electrostatic headphones, Grado Reference 1 headphones, and a Grado headphone amplifier.

Kubala-Sosna Emotion, Harmonic Technology CyberLight, Harmonic Technology Magic 2, Dual-Connect interconnects, Dynamic Design THB Nebula, Soundstring, Kimber Select balanced, Kimber TAK phono AG, Kimber Hero balanced and single ended interconnects, and Acoustic Zen Silver Reference II balanced interconnects. Kimber D-60 Digital Interconnects. Kimber Select 3038 Silver, Kubala-Sosna Emotion, and Harmonic Technology Magic Reference Silver speaker cables. Kimber Palladian, Tara RSC and Decade, Tice, Soundstring, and Kubala-Sosna Emotion AC power cords.

Monster Reference 350 Mark II v2 Power Conditioner, World Power Power Wing, Tice Clock, and Audio Prism Quiet Line IIs. Cable Cooker 2.5, Winds Stylus Pressure Gage, Bedini Ultra Clarifier, VPI Record Cleaning Machine 16.5. Audio Magic's Quantum Physics Noise Disrupters.


It fits right smack dab in the very center of HT's loudspeaker cable product line, and is their best all copper, single crystal formulation. The bi-wires are connected at the amplifier and are two separate lengths of low pass and high pass cable for most of its 8 foot length. They are terminated with top notch spades at the amplifier, spades for the low pass leg, and locking bananas for the high pass leg. All strands of the 6 nines pure copper are floating in Teflon tubes with air dielectric. They require about 100 hours of break-in for top performance, but sound very musical right out of the box. They sell for about $1330 in this aforementioned configuration. None of this prepares you for the performance of this very moderately priced wire …priced less, all in all, than most single meters of the ultra famous audiophile stuff.

What if I told you it sounded more realistic, harmonious, and extended than Kimber Silver Select Speaker Cable at 400% MORE $$'s? What if I told you I had $20k worth of high end exotic speaker cable gathering dust in my closet as a result of hearing the Pro-9 Reference? I understand from Jim Wang, CEO of HT, they built into this cable everything they have learned about pure copper formulations and windings since they went into business. I hear this and am very impressed. HT has created the most colorless, continuous, organic all copper cable in their history or maybe anyone's history. What a bargain! The Pro-9 Reference now makes it possible for nearly every audiophile to maximize their amp/speaker relationship without spending more for the cable than they spent on the speakers!

I've had experience with all kinds of exotic metal combinations for speaker cables and have settled on 100% copper as my all time favorite. Both of my reference systems are wired in all copper. I don't understand how HT can market this very serious and complex cable so inexpensively compared to others that cost so much more and sound very similar. That's unimportant. What is important is that this new addition to the HT line is a sonic overachiever and an involving sounding cable all around.

The Highs

With airy, delicate definition and extremely smooth performance, these are extraordinary cables for use with twitchy tweeters and the like. Try these with ceramic, beryllium, electrostats, etc. for superb results. Their seamless connection of highs and mids is even mannered and right sounding. You get a marvelous sense of depth and ambience with great control. They are near state of the art in overall performance in this important range.

The Mids

I have no criticism. They are evenly mannered throughout, with no obvious colorations to note. Lots of power and control in the mids, you'll hear oodles of definition comparable to many super expensive brands. Again, these are very, very musical unless your source is not. Mine are, and I wanted for nothing as I spent hours and hours auditioning the 9's. Overall balance is mid hall with lots of ambient air and a total lack of etch.

The Bass

Superb! In high or low power setups, you get powerful, deep, textured, articulate bass. They are wonderful for SET, and by contrast, solid-state systems. Almost the best you can get in this range at any price, I have rarely heard textures and definition from 20-250HZ as realistic and homogeneous. Nary a lump or bump, the Ref 9s are magical as bass wires.

Don't take my word, try them for yourself. You will be shocked at their performance!


The brand new Harmonic Technology Pro-9 Reference External Bi-wire Single crystal Copper Speaker Cable brings a price/performance breakthrough to audiophiles. I was gob-smacked when I first heard them and have yet to recover. For $1300 for a bi-wire pair, you can't go wrong! From 20-20,000 HZ, you'll get purity, evenness of tone, superb definition, harmonious performance, and powerful control the equal of cables costing 4 times more dough. Recommended for reference systems at economy system pricing, these are the first less costly speaker cables I'd actually use myself. HT is famous for bringing high value products to market. The HT Pro-9 Reference puts them squarely in the hall of fame! Robert H. Levi

Pro-9 speaker cables
Retail: $1300 a pair

Harmonic Technology
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