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Positive Feedback ISSUE 23


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Dear Robert H. Levi,
I've been reading Positive Feedback online for quite some time and I came to know of a lot of products that I've never heard before through your wonderful website. Let me thank you from the bottom of my heart for the wealth of information that you and your contributors are imparting through this great website.

I currently reside in Saudi Arabia and there are only a handful of so-called high-end products that are sold in this part of the world. I read your review of the Nuforce 9 & 9.02 amps and I am really interested. May I ask you, are they in the same league as Audio Research?

Eagerly awaiting your reply,

Yours sincerely,


Dear Jocy,

As the answer to your question hinges on the kind of loudspeakers you may use and the kind of music you listen to, I'll try to be helpful without that key information. Within its price range, the NuForce Amplifiers are tip top of the heap. They will out perform all competitors, solid state or tube, producing at least 200 watts per channel that I know of under $3000 per pair. This assumes your speakers are 87-89 dB efficient and you listen to bold, dynamic music. Speakers 90dB+ efficient may be candidates for lower power vacuum tube [valve] designs which have certain imaging and textural qualities that the NuForce's do less well. Audio Research is a superb manufacturer of amplifiers and very recommendable. To equal the power output of the NuForce 9.02, the tube unit from ARC would be 4 times more expensive [in America.] It would have sonic advantages I believe, but certainly not 400% more sonic return. The 110 from ARC at 100 watts per channel is $3000 in the US, and offers a richer, warmer presentation than the NuForce should that be sufficient power for your speakers.

The NuForce is a cutting edge solid state design and a stand out new product. It is so advanced, you would have to go to the solid state Pass X350.5 at $8000 US to beat it sonically by a small margin. At only 12 pounds each and highly flexible with both balanced and single ended inputs, it will not fail to please. At only $2500 US for the mono pair, they are the deal of the century. I love ARC, but just wait till you hear these NuForce 9.02 babies sing their tune.

All in all, you can't go wrong! Remember the first law of High Fidelity, "You never know what you are missing." Without samples of both brands in your system, whichever is in place will sound great to you.

Best regards and wonderful listening always,

Robert H. Levi

Mr. Dudious may want to add the Mercury Living Presence CD of the Concierto de Aranjuez played by Angel Romero, brother of Pepe to his list of excellent recordings of this piece - #434 369-2 Rodrigo/The Romeros with the San Antonio Symphony conducted by Victor Allesandro.

David L. Handler

Hello David...

Yes, that's an excellent performance; I have the SACD of this recording, and I value it highly.

Thanks for sending this along; I'll cc: Max to see if he wants to comment, as well.

All the best,


Regarding the Concierto de Aranjuez, which has become one of the most frequently recorded of 20th century guitar concertos, I'm sorry that I couldn't have mentioned each. Certainly I have left out many of other people's favorites. Mea Culpa. But as YOE points out, the Romeros do a great job on nearly all their recordings, and you can't go to far wrong with one of theirs. Like I said, you'd have to be a malicious evil-doer to mess up a masterpiece on purpose, but short of that, most any capable guitarist (acting in good faith) will get good results if he sticks to the score and just plays it—the music is that good. Sorry if I didn't mention everyone's favorite.


Dear Sirs,
Hi , I've read loads of archives, printing them out, reading them on my train journey home ...result = I've stopped buying HIFI Choice and HIFI + !

I'm sure you get many emails like this - but here are some of the things I would like to see:

1) Review - Prima Luna Prologue 2.
2) KT88 shoot out.
3) Comparison between red book on high end CD player and SACD on cheap DVD/SACD player—i.e. how much do you have to spend on an SACD player to beat the red book layer of your high end CD player—I know of no-one who has done this, which amazes me.
4) Article on Pure Pleasure excellent new vinyl reissues.
5) An article on Stewart Pinkertons $10000 cable challenge—see, Google Groups—he claims under DBT conditions no-one can tell the difference between cables. And I would LOVE you to take him up on it.
6) How does a 30 year old valve amp (i.e. Quad II, Leak etc) compare to a new Chinese valve amp.
7) Linn Ikemi.

just ideas
keep up the great work

be cool


Max Dudious here, with some tentative answers to just two of your tough questions. When you read them you might understand why most writers will duck them. But I'm feeling courageous today. KT-88 shootout: I guess you mean you'd like to break down what the strengths and weaknesses of the sounds of various manufacturer's KT-88 tubes amount to. Let's say some are "drier" (greater emphasis on mid-treble range), and some are "warmer" (emphasis on mid-bass range). A system, or room, or interaction of speakers in a room, that already emphasizes the mid-treb region would not like the drier tubes, and might do better with the warmer tube. So, any shootout between the various manufacturers tubes would have to keep all that in mind. Of what does the shoot-out referee's system consist? Is his system warm or dry? He would have to specify each of his components, and describe the acoustic of his listening room, and then try to figure out how this or that brand KT 88 combines with the rest, and to be really "scientific," he'd have to quantify everything through a sound pressure meter, and/or a computer. Do you see what I'm getting at? To do even a passably good job would take a lot of time and attention to detail, and the results would be met with instantaneous letters saying, "I got the exactly opposite results when I tried those tubes in my system." 

Just for one small difference, damping factor. If a KT-88 driven amplifier's tubes had even the smallest variance in their specs (compared with the O.E.M. tubes) the damping factor would be changed. The amp could be seen as having bass that was too floppy, or too stiff. This would be considered a problem of the tubes. But if, say, one little value on one crucial resistor were changed the sound might improve. Does that imply there is something wrong with the amp? No. It is just that one tube might sound as good as another if the damping factor were adjusted to make each sound optimal. So it would not reflect on the "goodness" of the tubes. But if you had chosen to put the KT-88s in an amp, which by blind luck made a more fortuitous match with the speakers it had to drive, everyone might say Brand X beats Brand Y by a mile. So, you'd think you're investigating tubes, but you'd be comparing damping factor, or the interaction of the amps with the speakers. What could you say? How could you avoid being involved in a series of such snarls?

The same sort of thinking would impinge on comparing old U.S. and U.K. amps with new Chinese amps. What output tubes? What damping factor? How dry the room? How high the moon? Metal film resistors? Polypropylene capacitors? What speakers would you listen to? Dynamic or Electrostatic? Whose software? etc. etc. You could get just about any sound out of either of those amps. And we haven't mentioned interconnects and speaker cables.

That said, although the tests you's like to have performed are beset with problems, there is usually some consensus arrived at after lots of folks diddle with tube rolling and the like. For example, Brand Z is "noisy," Brand W is "glassy sounding," Brand V is "wooly" on bass. I'm not sure how this is arrived at. Maybe all the guys at Audio Asylum take votes, or over time the consensus is arrived at. I remember back a ways, some early Asian tubes came through with their grids all askew, while others did not have the plates and the grids parallel, etc. It seems the manufacturers didn't care enough (probably didn't understand why it was necessary) to get these basic elements correct. The tubes in question did not sound good. They sounded "off" but not terrible. Constant vigilance is the price of great sound. You have to sweat every detail. Who first said? "The devil is in the details." Mies van der Rohe? David Robinson? The Giz? I'm not sure, but I'm saying it here.

I'm also saying that anyone who claims this or that tube blows the others out of the water is displaying his naivete. He needs to go on to Tweaking 201. When someone says that Brand X tubes have come to be known as good, it usually means over time, many guys, with many different systems, have tried Brand X and gotten good results. The reputation builds slowly over time. After a while it becomes accepted that Brand X is good in most equipment, with most systems. But to make a consumer's report table with different brand names is, in my opinion, just one data point which would be challenged the moment you published it. If you don't believe me, try it yourself.

Hate to be the one to tell ya.

Max Dudious

In reference to the Acrolink/Oyaide review, I want to thank Victor for reviewing anything with Edgar Varese's piece, Ionization by the LA Phil conduted by Zubin Mehta! I love Varese, ever since I was clued into to him by Frank Zappa.

Next, try Ligeti.


You say of the BAT VK-51SE and 600SE:
The BAT pieces are easily the finest amplification chain I have ever heard; period. The VK-600-SE simply has no shortcomings, none. Transparent finesse, silky smoothness, confident refinement, and virtually limitless power and dynamic range without compromise of any sort, BAT may not be enjoying the "boutique" chatter directed towards lesser pieces, but forget about fashion and listen to these two extraordinary components TOGETHER and listen to them balanced.

Running BAT gear single-ended is like putting Bridgestone tires on a Ferrari.

Just for the record, Formula One Ferraris run Bridgestone tires. That is why they won the U.S. Gran Prix in 2005. Michelin couldn't supply its teams with a safe tire, so only the Bridgestone teams contested the race.

However, I do agree with the point you are making.

Best wishes,

Roger Hillas

Hello Roger,

I know they do, check out Mr. Ferrarri's comments that the tires were the problem at "each of the corners" of the car.


Good joke at Bridgestone's expense, and pardon my nitpicking.

Any particular reason why you tested the BAT VK-51E with the solid-state power amp rather than the VK-75? I ask because I'm thinking about going the BAT route but don't need the extra power solid state offers. It would be to drive Sonus Faber speakers, probably Guarneri, maybe Cremona. I listen to classical, especially opera, in a 21 x 17 room with a 7 foot ceiling.


Hi Roger

Thanks for the comments.

I would love to do the 75's and I will approach BAT about them.

However, the VK-600 is way more than just being about power. You simply have to hear it to understand. But, even very efficient speakers benefit from huge amounts of current, high control, and endless headroom.


Thanks. I had linked directly from the BAT site to your PFO piece. Having now read your actual review of the 600, I see what you are trying to do and why the 600 is the one to do it.

You're a very gifted writer and immense fun to read. You also have good judgment. The combination of the two is rare.

Keep up the good work.


Dear Sirs,
Your online magazine is fantastic and nowadays my No 1 point of reference, although I consume two American and one English paper magazine as well as two other online magazines. Therefore, it is the more frustrating that your text format is optimised for the American size paper. The consequence is that the rest of the world cannot print your excellent reviews (which I take the liberty of doing every now and then to be able to read comfortably) without missing the last word or two on the right hand side of the text. Please help!

Mikael von Schedvin
Stockholm, Sweden

Thanks for the compliments. I was unaware that Eruope had different paper/printing sizes than the US ..even so, I do not see how I could make the site universal for one and all. The site is set to print to an 8.5 x 11...

Dave Clark

Dear Sirs,
Everyone at Furutech appreciates Robert Levi's review, including a dedicated band of enthusiastic engineers under the estimable Mr. Frank Yoo and his Tokyo-based assistant Mr. Graeme Coley.

The e-TP80 is not so much a conditioner as a power distributor with filtered and non-filtered mechanically decoupled star-wired outlets. The new e-TP609 offers three sets of unfiltered outlets—fine for amps as well as the front-end—and both feature the ever so gripping Axial Locking System that optimally hand torques each duplex against its surrounding anti-resonance material. Both feature a layer of EMI-eating GC-303, also found wrapped around Furutech's Reference cables.

Bob, those are LED on the right panel! The bottom one glows green when power is present, and touching the center nub will light the red LED above it when polarity is correct.

Furutech's heavy science and engineering approach lavishes attention on each and every aspect of power and signal transfer. Just handling one of their lush silver-plated bronze phosphor RCA male spring filaments is amazing. The unique Ground (Earth) Jumper System eliminates magnetic distortion in power connectors. We know that current flowing in a cable and connector creates an encircling magnetic field. Furutech engineers found this induces current flow in the screws holding the connector and shell together, creating an interfering magnetic field. The Ground Jumper System conducts screw-borne currents to ground. Strict attention to details. And all metal materials are deeply cryogenically treated then ring-demagnetized. You can keep your cables, connectors and CDs that way with an RD-2 CD and Cable Demagnetizer or the soon available LP-sized DeMag! Anti-stat ion guns will be a dime a dozen on Ebay!

For Furutech,
Jonathan Scull
Scull Communications

I just want to say thanks―having used the web for over 10 years this the is best read I've ever found.

I really hate my job at the moment and feel more than a little depressed, but your excellent archives are just about keeping me sane.

thanks once again


Mr. Robinson,    
I haven't had the luxury of reading PFO for a while. A LONG while. I noticed you have the VR-9s. Has a review been done on these excellent products?


Hello JD

The VR-9 SEs are excellent products all right a matter of fact, I consider them to be exceptional. My review of them is in the works; stay tuned. PFO's Mike Lavigne also has a pair in his listening room; if he bestirs himself, you may hear from him, as well.

All the best,


Hi Marshall,
I read your review of the Harmonix spike bases, but those are too much $. Prior to the various tweaks, have you played around with the height of the spikes or do you simply leave it at the highest position?


Hi Howard

Prior to all the tweaks, I did experiment briefly with the height of the spikes on the Kharma CRM 3.2 FE. Adjusting speaker height can effect small changes in the tonal balancethe closer to the floor the darker the palette. But higher up gives it more room to breathe and better tone.

But I have good news for you. There is another spike base available at less than half the cost--the TAOC PTS-F Spike Plate set (MSRP $300/set of 4). These work about as well as the Harmonix. I actually prefer them. You don't get the Harmonix acoustic tuning, but you do get tons of weight and a more neutral frequency sweep. Check out my review for more info:

Happy new year to ya, Howard

Marshall Nack

Hi Marshall,
Yes, I've read all your Kharma tweaks. I do have thick carpets and you have hardwood floors? Since there wasn't any directions in terms of adjusting the speaker height. I tried playing around it a bit, and like you said, every time I lower the speaker height just a bit, I find that tone suffers like you said. But then at the highest height, it does sound thinner. It's made even more difficult by the fact that when it's not at the highest setting, it's difficult to determine whether things are uniform.

Removing those spike plates were a no go as well. I'm led to believe that the spikes are intended to be at its highest positions. May I ask how your speakers are positioned? Like how far apart and distance from the back wall etc.? and did you like the Taoc spike plates or the Harmonix RF-900? Ever tried the Black diamond racing ones?


Hi Howard,

I have a LONG, rectangular listening room-32' long x 12' wide x 8' high-ideally suited for the rule of thirds: speakers are positioned one third into the room and about 24" from the sidewalls to the edge of the front baffle, facing straight ahead; the listener sits another third into the room. I have hardwood floors.

And you have a problem with the carpeting. Usually it's recommended to use long spikes that can penetrate through to the floor. But then your're faced with needing something under the carpet to receive the spike points.

Given the carpeting, none of the spike receptacles are a good option. Have you considered using a hard platform above the carpet? TAOC makes just such a platform, the Sound Create Board, and I can vouch for its salutary effect.

BTW: the Harmonix and the TAOC spike bases are the best I've come across.

Marshall Nack 

Hi Dave,
Thank you for posting such an extended photo essay on the Walker Audio Proscenium Turntable. For you to devote so much space to the essay was a wonderful gift to the audio community and I've enjoyed looking through all of it and reading your comments. As an owner of this turntable, it was a delightful reminder of the day Lloyd and Fred spent at our home setting up the turntable: looked like exactly the same process! I hope you won't mind to know that I've copied YOUR photos for our scrapbook since we had none for that day.

This turntable is EVERYTHING you've described. My words simply have never captured the full scope of what this turntable accomplishes, but your words came closer and they match my experience with this turntable on every point.

If you think your readers may be interested in some additional comments from owners that match to your own assessment of this turntable, here are some links to post by owners at both Audio Asylums and your own publication a few months ago:

And let's not forget the article Albert Porter contributed to PFO in Issue 17 on his Evolution of a Source, a lifetime search that ended with his purchase of the Walker Proscenium:

Thanks for this great essay!

Rush Paul

Hello Rush...

I appreciate your kind words about my essay on the Walker Audio Proscenium system. It was a long time in the making...over a year...and took a great deal of time and thought to write. Paradigm-shifting designs are that way; the significance of the change makes brevity impossible. Lloyd and Fred have done an astonishing job of taking their design philosophy to the limit, and it required a lot of words and photographs to describe their accomplishment properly.

Unless you've actually sat down and tried to convert impressions of what you hear and feel into expressions of what it meant a way that will resonate with others have no idea of the difficulty of the task.

It's all about impression and expression, you see.

On one hand, you must be possessed of experienced, trained senses...what I have called "sensibility" discern the worthy and the unworthy. (cf. Hebrews 5:14: "But solid food is for the mature, who by constant use have trained themselves to distinguish good from evil.") This is what I mean when I speak of audio connoisseurship: the conversion of mere sense (which most of us are born with) into sensibility. A person with sensibility can form coherent impressions that are significant.

On the other hand, you must master language and writing to the point of being able to convey richly, and with some degree of power, those impressions that you've formed. A person with the gift of writing can embody his or her hidden, internal world through expression. Like any other gift, writing ...the gift of the word ...must be used, or it will atrophy; the senses must continue their training, or they will lose ground. There's a pound of perspiration for every ounce of inspiration in all the arts.

The combination of impression and expression is what it takes to review or critique in any domain, including fine audio.

Some people have the sensibilities, but cannot write. Some people can write, but do not have the sensibilities.

Some people have neither; a relative few have both.

And impatience or laziness will deprive even the gifted of their gifts.

Enough for now, I think. Were I to write more, it would be another essay....

The links that you sent along are very helpful; Audio Asylum can be a very valuable resource for audiophiles. It is a trove of the collected wisdom (and the collected unwisdom!) of audio lovers from all over the globe; I recommend these links to our readers as additional takes on the virtues of the Walker Audio Proscenium system. Albert Porter's article in PFO is also a useful reminder.

You're certainly welcome to use my photographs for your scrapbook, Rush; I'm glad that it will help you to recover the memories of your time with Lloyd and Fred.

All the best to you in your audio journey...


Hi David,
I just finished reading your article regarding your Sony SCD-1 upgrades with great interest. I have e-mailed Richard Kern to inquire if he has upgrades for Sony C555ES SACD and Audible Illusions L2.

I have a question for you though; have you heard of David Schulte of The Upgrade Company? Have you had the opportunity to listen to any of his upgrades?

Thank you in advance.

Merry Christmas and Happy New Year.

Ben Licera

Hello Ben...

I don't know if Richard Kern is modding those players, but I do know that he does very fine work.

I've never heard of David Schulte or The Upgrade Company, so can't comment on that. I am personally familiar with the work of Allen Wright and Vacuum State Audio (, Paul Weitzel and Tube Research Labs (, Dan Wright ( and Richard Kern ( These folks each have their own philosophy and approach to modifications for SACD gear, specialize in particular makes/models, and all do fine work in their selected domain. I can recommend any of them with confidence.

Merry Christmas to you, Ben.