16th December 2023

Looking to reduce noise from the HiFi chain, Paul Rigby grabs a set of RCA and XLR plugs from the Japanese company

There may be one or two of you out there who have just sighed in exasperation. “Oh good grief, he’s at it again with his rip-off expensive toys again. Why does he bother?”

Or maybe you’re not. Maybe you also know how anti-noise accessories can benefit your HiFi’s sound output. Maybe you’re one of the enlightened listeners out there. 


If you are a doubting Thomas though, let me say this. A few year’s ago, I grabbed my what, £50k high-end reference system? More, actually. £80k? I dunno, I haven’t counted up in a while. 

I pulled out all the anti-noise “toys” from it. I have quite a few. All of the grounding accessories, damping feet, isolation platforms…the lot. 

Then I listened to it, fresh. With new ears. Result?


My system was basically unlistenable. Completely unlistenable. To me, that is. To my ears. It sounded pathetic. Horrible. I preferred to pick up a £100 digital audio played and stick a pair of ear buds in my lugholes instead. That sounded far better.

Why? Because I knew what had come before, basically. 

All that component money. All those thousands of pounds on amps and speakers and the like. Don’t mean a thing because my system no longer had that swing. 


It had diddly squat. Because it was swamped by parasitic noise, so all of the good sonic stuff was masked. Trapped under sonic rubbish. You never got to hear most of it. To repeat, it was there. I just couldn’t access it. 

Instead, I heard parasitic noise: shouty mids, plump bass, tinny treble. It sounded horrible. 


So I plugged my basket of anti-noise “toys” back in, on and around my HiFi. Listened again. Took a deep breath and relaxed for the first time as the detail returned. The noise floor dropped. Clarity appeared. And so on. 

When tackling noise (and there’s plenty of variants out there from vibration and its associated microphony, there’s airborne Wi-Fi, radio and mobile signals, there’s the rubbish from switch-mode power supplies polluting the mains, etc. 


For me? In my experience? As a general HiFi dictum? I would say this.

Accessories are just as important as the main components.

Just as important. Got that? 

Now look, there is good and bad in all HiFi. That includes anti-noise accessories. Some don’t work at all. Some go so far down the road but don’t do enough to justify the price. Then there’s a group of serious players out there.

Furutech, I have found over the years, after multiple reviews of their wares, is one of those serious players. It’s stuff is not cheap. It’s downright expensive, actually. Thing is though, it’s often more than worth the money. I have Furutech anti-static, anti-magnetic and damping accessories in and around my system and I wouldnt be without them. 


So I was interested to see and hear these little plugs. To see if they did the job. To see if they were worth the asking price. And let me remind you that these are high-end products, so they cost a lot and should be viewed from that perspective.


Called passive signal line optimisers, these little plugs are part of the company’s Clear Line range, first launched in 2020.

Small enough to hold in your hand, they look exactly like termination plugs, chopped off the end of a cable. And that’s because that’s basically what they are. Well, on the outside. They arrive with either RCA, XLR male and XR female connection plugs. Thing is, though, these plugs are filled with anti-noise tech, then sealed at the base. 

The idea is that you insert these plugs into an empty socket. Any socket that fits. You don’t have to worry about electrical shorting or any of that. You can plug them into anything: an amplifier, DAC, CD/DVD/SACD player, whatever. You don’t switch them on, they are not active. They are passive items. And really? After years of trying anti-noise accessories, I prefer passive to active. Some people reside in challenging urban environments (I have been such a person in the past) and don’t have a choice, they have to go active to bulldoze the sound through the excess noise. And I understand that. But given a choice? I prefer passive.


And the passive tech inside each of these plugs is Furutech’s own NCF or Nano Crystal2 Formula.

According to the company, NCF features a crystalline material that generates negative ions that eliminate static. It converts thermal energy into far infrared. The upshot, says Furutech, is to damp, remove noise and, as a consequence, increase detail. 

To offer a mite more information, Furutech states that the plug is Rhodium-plated, includes pure copper, one-piece construction conductors injected with heat-resistant NCF liquid crystal polymer resin. Included too, it says, are audio-grade ceramic capacitors treated to suppress resonance and eliminate noise induced at the equipment’s input or output terminals.

Even the outer body reportedly includes NCF liquid crystal polymer resin, incorporating nylon, fibreglass, nano-sized crystalline piezo ceramic particles and carbon powder within a multi-layered NCF, non-magnetic stainless steel and carbon fibre shell. Phew!


In use? You should – according to the company – be able to hear sonic effects immediately but as the plug drains noise, that effect should improve over the following 24 hours. 

So let’s give these things a try then.


I removed my usual anti-noise concoction to avoid any false readings while using other products. 

I then began with CD and Bing Crosby’s A Southern Memoir, a 2010 reissue via HLC and the track Carolina in the Morning. Apart from the Crosby vocal, he is backed by a jazz orchestra comprising brass section, percussion piano and more. 


I happened to have all three of the Furutech plug variants to test so I plugged one of the RCAs into a rear of my Benchmark DAC, connected via coax to my Audiolab 6000CDT. 

In sonic terms, I could hear an immediate drop in upper midrange glare that, especially at higher volumes, previously hung around the Crosby vocal. Despite his baritone delivery, his vocal did have a straining dazzle attached to it. The Furutech largely removed that issue. Brass was also calmed now, while the treble opened up, allowing more reverb into the soundstage. 


One reason why I selected the Benchmark for this test was that it allowed me to also plug in a female XLR unit into a spare XLR output socket. Doing so increased the sonic improvements, adding new space and air around the soundstage improved the clarity, giving the midrange output a relaxing feeling. 

And that’s half the point of these things. Experimenting with different sockets and different components. Trying different sockets to find what works best and where.

You see this lady, above? A telephone operator, plugging in a gamut of plugs into a board to find the right connection? That’s what you need to do when using these Furutech plugs. Keep ‘plugging away’ until you find the right connection.

Different components can benefit in different ways. Different component manufacturers can also perform in different ways too. It’s best to spend time with units like these to see what connection provides the best sonic response. 


In my case, I found an even greater performance response by hitting both RCA and XLR circuits at the same time with two plugs inserted at once. I noticed that the ride cymbal off the back of the drum kit took a greater role in the mix with two Furutech units fitted. 

So far, so good then. I then unplugged both units and inserted the RCA plug into my pre-amp. 


And here’s a good example of success through experimentation because my response to plugging a RCA unit into a spare RCA pre-amp input was a little lukewarm. It was fine. Just not sparkling. When I transferred that same unit into a spare RCA output though, I found the performance to be more effective. Upper midrange glare was better reduced. Tonal balance was much more effective into this position. 

The best response though, for my pre-amp at least, was using a balanced unit but using it on the built-in tape loop in that pre-amp. That was the sweet spot. Cymbal hits were delicate and fragile, vocals were well modulated, brass was evenly toned while the piano danced across the soundstage.


Moving to vinyl now, I played the album, Second Flight from Pilot, indulgent and nostalgic pop tones from my childhood. And tried a RCA unit in my phono amplifier. There was a distinct calming, right across the midband and it came as a relief, let me tell you from the OG sound of bright and nasty. Especially at higher volumes. The lead vocal was no longer on a  knife edge but melodic and emotional while the synth backing flowed instead of crackled, especially around the treble area. 

I then added a male XLR plug to the tape loop circuit on my preamp and that calmed the sound even further allowing bass – not a strong point on this track – a great chance to show itself and to balance the song as whole.


I’ve said this before and I’ll say it again, accessories like the Furutech don’t enhance the sound quality of the sound, per se. What they do is to remove the sonic rubbish that masks the sound of your turntable, your streamer, your amplifier or whatever it may be. These plugs, like other anti-noise ancillaries, allow your HiFi to perform as advertised. 

As such, these plugs and accessories like them can be sonic life savers. They can be the difference between making your HiFi usable or not. As simple as that. 

And because of that, the price is either extortionate or it’s worth every penny. Again, that depends on you and the performance of these plugs in your system. 

That is, how effective these units will be in your system depends on your system and you, to be frank. I recommend trying them out, experimenting, plugging them in every available slot, living with them (because you need a 24 hour run in on each socket to enable each plug to work properly) and then deciding from that 24-hour, run-in point. Some socket positions, some components even, will be more effective than others.

For me? They had an immediate effect that only improved as the hours progressed. The more units I plugged in, the better my HiFi sounded. So my HiFi chain was running with six of the things running simultaneously at one point. And at that point? The sound was smooth. Very smooth.



NCF Clear Line RCA: £205 per unit 

NCF Clear Line XLR (M or F): £260 per unit

Website: or

GOOD: compact design, easy to install, low noise, sonic improvements 

BAD: nothing