I’ve spent many years working to reduce obvious and nonobvious noise in my audio system. The former includes easily audible hums, buzzes, and hisses. The latter includes the subtle sounds that fill the spaces between notes and that often remain unnoticed, that is until they are gone. Indeed, my system runs very quietly. But first things first.  

I wasn’t sure what to expect when I received a review sample of Vera-Fi Audio’s Main Stream Master Class Parallel AC line conditioner ($295 USD), but I was intrigued. According to the company, this product filters AC noise when it's placed in parallel with an audio system. I liked that, as I hoped that since AC power wouldn’t pass through the Main Stream (i.e., sit in series), the possibility that the waveform’s integrity would be degraded would be minimal. 

Vera-Fi doesn't give away too much about how the Main Stream’s works. It does say, though, that it operates in the frequency range from 10kHz to 20kHz, particularly in the higher part of that region. This, according to Vera-Fi, is the area which is commonly affected by a home’s many electrical devices. Also, Vera-Fi states that Main Stream needs run-in of up to 400 hours to reach peak operating performance, though the company states much of its benefits are evident after about 40-50 hours of operation.   

Examining the Main Stream’s exterior didn’t reveal much. Rectangularly shaped, it roughly fits into the palm of one’s hand and contains a blue LED power indicator light that’s located just above its prongs. 

My winding road to noise reduction 

As noted above, my audio system runs quietly. I have achieved this state by carefully grounding the system and using the following devices to achieve several levels of conditioning: 

• Pi Audio UberBuss AC power conditioner that plugs into an AC wall duplex. My power amp and preamp plug into this component.  

• Monster Power HTS2000 power conditioner that I plug into the UberBuss. Wall warts and other power supplies for various devices in my system (e.g., turntable, DAC, and phono preamp) plug into this power conditioner. 

• Belkin PivotPlug 12-plug surge protector that plugs into the Monster Power unit. The devices that plug into the Belkin include such things as my television, video streamer, and a pair of network switches. 

  
  

The result of this somewhat complex power product configuration is that even with my most sensitive speakers (rated at 98dB) and a single-ended tube amp at full volume, I can detect no noise of any kind, even when my ear is positioned an inch or two from the speakers’ drivers. 

Plug, Wait, and Play 

The first question was where should I install the Main Stream? Vera-Fi recommends plugging it “into the mains socket closest to the component,” so I tried two places – first, the AC duplex where the Pi Audio UberBuss plugs into the wall, and then one of the outlets on the UberBuss. After a few days of listening both ways, I preferred the results when the Main Street was plugged into the UberBuss. 

The proof and the pudding 

What did the Main Stream do in my audio system? Well, people who don’t pay attention to things other than frequency response and loudness would probably say that it did nothing. In fact, I detected no change in tone. While that wasn’t surprising, it was welcome. So, what did I hear? 

Though subtle in degree, the Main Stream improved my system’s transparency and ability to retrieve small details in a way that I quickly became accustomed to. Everything sounded a little bit clearer and cleaner. Both the leading edged of notes and their decay were clearer and better defined. I liken it to looking through a window and then opening to look outside. Small details were suddenly more apparent. 

An example of what I heard is the 24/96 stream of Jack Johnson’s song “Better Together” from his album In Between Dreams (Qobuz, Brushfire Records). This is often the first track I turn to when trying a new product in my system. Now even during the first minute of the track, I noticed the Main Stream’s improvements. For example, at about the 40 second mark there are very lightly played cymbals that in some cases are barely perceptible. With the Main Stream in my system, those cymbals, though still faint and distant, sounded clearer and more distinct. 

Retrieving a very early UK pressing of Pentangle’s LP Cruel Sister (Transatlantic Records, TRA 228), I queued up the album’s first track, “A Maid That’s Deep in Love.” With the Main Stream in use, Terry Cox’s gently struck triangle and Jacqui McShee’s angelic voice were each set against a clearer, cleaner background. Further, Danny Thompson’s double bass had more weight and clarity, and the soundstage sounded a bit more open. 

The Main Stream’s benefits were apparent regardless of the recording on both analog and digital sources. The benefits were greater, though, while using my 15-wpc Antique Sound Labs KT88-based tube amp than they were with my 100-wpc solid-state Burson Timekeeper Virtuoso amp. Of course, that may be because many solid-state amps have a reputation for generating less noise than do tubed ones. 

I understand that some people find power filtration devices in general to be nonsense and that’s fine for them. For me though, I approach the product (as I do any) as an agnostic and let my ears and experience lead me to a conclusion.  

In this case, Vera-Fi Audio’s Main Stream line conditioner made a subtle, but audible and positive difference in my audio system. Its $300 asking price is not paltry. However, the question that I ask is that if I remove the Main Stream from the system, is there anything else at a roughly similar price that could provide similar sonic improvements?  Having gotten very accustomed to the Main Stream’s effects, I wouldn't want to take that chance. 

Vera-Fi Audio Main Stream  Master Class Dynamic Parallel AC Line Conditioner  

Price: $295 USD 

Warranty: three years (parts labor included) 

Dimensions: 4.5” x 1.75” x 1.75” Weight: 12 ounces 

Vera-Fi Audio LLC. 

Newbury Park, California 

https://verafiaudiollc.com/ 

Associated Equipment  

• Digital Source: Geekom NUC i5 Mini PC server, JRiver Media Center 33, Qobuz desktop app, iFi NEO iDSD and NEO iDSD2 DACs, iFi USB 3 and Audioquest Jitterbug FMJ filters, iPurifier2. 

• Analog Source: Linn LP12 turntable with Ittok arm, MOSE/Hercules II power supply, Dynavector 10X5 MK II Low cartridge, iFi Phono2 phono preamp, Sound Organization wall-mounted turntable shelf. 

• Preamplification: Khozmo stereo passive preamplifier with AMRG ladder attenuator. 

• Amplification: Antique Sound Labs MG-SI15DT-S or Burson Timekeeper Virtuoso power amplifiers. 

• Loudspeakers: Tekton Perfect SET 15 speakers on AVRoom Services EVP isolators or Magneplanar .7. 

• Power Conditioning: Pi audio UberBuss, Monster Power HTS 2000, Belkin PivotPlug 12-plug surge protector, connected in series 

• Cables: Vermouth Audio Black Pearl interconnects, Vermouth Audio Red Velvet or Audioquest Type 5 speaker cables, Straightwire USB and iFi Gemini twin-head USB digital cables, Standard OEM power cables. 

• Component Racks: Mondo Audio and Pangea Vulcan. 

• Accessories: Kinetronics anti-static brush, Pro-Ject VC-S and Spin Clean record cleaners.