Power Product Reviews

by Kevin OBrien on 05/01/2023


Power is important. Without power, the audio rack won't fire up. Sure. We get it... We all have power conditioners as we are proper 'audiophiles'. We do extreme things, considered as such by outsiders as 'extreme', because we just want the best sound we can get regardless of cost. These same 'outsiders' would not understand spending thousands of dollars on isolation transformers and such, or dedicated 20-Amp lines for our listening rooms, etc. This hobby just seems so crazy sometimes.

Enter Bill Stierhout, owner of Coherence Systems, and developer of a new power product line of components for AV enthusiasts. These are power products that deliver better results than just plugging gear directly into the wall. This new line of products is called ADD-Powr. But wait, you can still plug your favorite gear directly into the wall with Bill's products, or into your current power conditioner. You see, Bill's products induce a sag on your AC line by introducing an 8 Hz signal onto your home's entire power system. Treating the entire electrical system results in bettering even non-audio-related electronics, such as computer monitors and TVs. You don't actually plug your gear into Bill's Sorcer X4 Plus, you plug the X4 into your house electrical system, in parallel to your existing conditioner / gear. That's the idea anyway.


Let us gather some background information first, before we go further. Bill got his start helping professional recording studios in the early 1980s. With consoles and digital tape machines under his belt, he garnered himself a solid reputation in the Pro world. He would later enter into the 'audiophile' market in 1999 by developing Quantum Products, which is how QRT came to be. QRT stands for Quantum Resonant Technology. This is the same technology that Nordost purchased from Bill in 2008, along with Quantum Products itself. 

It's safe to say that Bill is not a newcomer to The HiFi Industry and his Add-Powr products are not to be taken lightly. Specifically, we are speaking to the ADD-Powr Sorcer X4 Plus. This is a type of "AC Harmonic Resonator", as Bill calls it. Bill was nice enough to allow us to purchase a review unit after meeting at the 2023 AXPONA event in Chicago earlier this year. Despite not truly understanding what Bill was telling us at AXPONA, we wanted to learn more and hear for ourselves what the Sorcer X4 could do. A review was definitely in order, so that's what we're doing here... and the results are interesting, and fascinating!

Throughout the results below, we will give some feedback from one of our YFS customers, Thomas. He also purchased an X4 for his system. He lives in Chicago, so it was an easy way to get an X4 without getting freight involved. Bill was kind enough to help Thomas at the AXPONA event itself. That brings up another point, Bill is easy going, and will never pressure you into a sale or lead you one way or another. We respect that. He was also patient enough to help Thomas with all of his questions and concerns regarding this 30-pound hunk of sophisticated metal. Patience is a virtue, and luckily, Bill has that in spades.

Above is the literature that comes inside the box. It goes into describing how to operate the X4, along with a few notes about its general workings. The X4 is not your typical power conditioner. This means you will not want to use it like a typical power conditioner. It needs to go to work on your AC power line, not on your gear first hand. It reads above that the X4 can be placed in several locations, but we noticed it had its best effect on our system when placed near our rack, plugged into a power outlet adjacent to our rack. We listened with the top off, in hopes to get the most out of the innards of the X4. This allowed us to 'expose' ourselves and our system to whatever technology was happening inside the X4.

During the evaluation period, we tried all sorts of locations and configurations for the X4. We tried plugging it into our voltage regulator and everywhere in between. Best results still were obtained by placing the X4 adjacent to our gear, plugged into a random house power outlet.

We power our isolation transformer, which our gear plugs into, from the referenced voltage regulator above, which supplies a steady 120 Volts to our system (+/- 1 Volt). This device also filters the incoming power, which helps things a bit further. An isolation transformer feeds our audio gear with balanced power (60V+ / 60V-) and provides some further filtering and capacitance. This ends up bringing our noise floor down substantially and helps breathe dynamics into our system. The balanced power allows our source gear to operate at its best, similar to a pro studio environment, with excellent, quiet, low-level detail retrieval. A common ground is also established between our components, eliminating ground loops & hum. This is our much preferred method of powering our rack, instead of just plugging straight into the wall. 

Luckily, the X4 works in tandem with the rest of our existing gear. So do not worry, there's no need to ditch your current investment in AV power products. In some cases, some conditioners will not be compatible with the X4. Namely, any RE-conditioner that re-creates the AC Sinewave (ie. PS Audio Powerplant). You have to exercise some caution when mating gear with the X4, but most of us should be just fine.

The X4 should be turned on and left in place for 15 minutes prior to making any evaluations. This is per the manufacturer. Although, we noticed a change in our system as soon as we placed the unit adjacent to our rack and turned it on. We used a solid audiophile-grade YFS power cord, not a cheapie from our local Box store (apparently, a good power cord is a must). Albeit slight, the change was there. It was for the better. The sound seemed to get more layered, allowing us a greater view into the recording. The sound field the speakers were throwing now allowed us to enjoy an even more expansive listening space, yet imaging solidified between the speakers. Again, these changes for us were slight. On the other hand, they were not slight for our friend, Thomas, in Chicago. 

Thomas was getting the same experience, but in much more full effect than what we were getting. Changes were not slight, but right there in front of him. They were obvious, right in plane sight, calling attention to themselves. We are still scratching our heads as to why?

We know everything in this hobby is system-dependent. That includes tweaks, cables, and pretty much everything in between. The X4 is no different based on our testing and evaluation. Results are all positive, with some users experiencing major changes to their listening, while others only experiencing minor changes. Your mileage with the X4 will vary, dependent upon your system. Your guess is as good as ours. We have no way to figure out how this 'ADD-Powr effect' works, but it doesn't work the same for everyone, as we all have different gear. 

If you have questions about the Sorcer X4 Plus, contact Bill directly. He is here to help. We rarely run into folks as nice as Bill, and it will serve him well in his future audio endeavors (and it already has). We wish Bill the best of luck with his new line of ADD-Powr products. Give them a shot. You have nothing to lose.  Bill promotes a 30-day trial on his website.  Very cool.

Thank you for spending your time with us.

Until next time...


by Kevin OBrien on 08/02/2011


I have heard from the audiophile grapevine that a sweet combination for a power reconditioning system would consist of a PS Audio Power Plant Premier reconditioner COMBINED with an Equitech Isolation Transformer for the ultimate power conditioning system for the ultimate audio and video experience. Well, I went ahead and did it. I know PS Audio has recently come out with the P5 and P10 power reconditioners but lets talk about the earlier Power Plant Premier that we are all quite familiar with I'm sure.

The premise of the PPP is that you can achieve a better audio/ video performance throughout your system by creating perfect, clean, reconditioned power for all your components. I never used to believe any of this until I tried a PS Audio P600 reconditioner back in 2005. All I could say was WOW. It made a huge difference especially in terms of soundstage width and depth as well as detail retrieval. The music just seemed to "hang" in the air in front of you when all your components were using "reconditioned" power.

Equitech provides a balanced power system by running 60V on the hot line and running 60V on the neutral line and carrying the noise on the ground. This is what recording studios have been doing for a while now. The normal convention in an unbalanced system would place 120V on the hot line and 0V on the neutral line and you still have the ground but supposedly considerable noise can be introduced into your system.

I heard a while back that an interesting audiophile experiment would be to try and incorporate an Equitech Isolation Transformer with a PPP. I couldn't help myself and I had to give it a try once the idea popped into my head. So what kind of results would this experiment yield? Pretty cool results indeed.

By itself, the Equitech 1.5Q is an exceptional product in my opinion. Unfortunately it does not remedy the problem of distortion infiltrating your system on the incoming line from your home's power. This is solved by first using the PPP to reproduce perfect, low distortion, AC power and then plugging the Equitech 1.5Q into it to achieve an even lower noise floor than the PPP can achieve.

Unfortunately, either of the products by themselves is not ideal. The PPP can control the output voltage to your components by turning the potentiometer underneath the unit. This is a dirty little secret PS Audio does not want you to know since some of the PPP units were damaged during shipping and this option could potentially be non-functional. Let's hope this isn't the case for you because 117V sounds absolutely great with tubed gear! The 1.5RQ cannot control the output voltage but drops the noise floor 20dB less than the PPP and adds the all-important balanced power output the newer power plants do not produce.

I must say, after getting my hands on an Equitech, I gave it a try and it was definitely worth it. The noise floor dropped a noticeable amount. Now whether it was the spec'd 20dB less than the PPP, I'm not certain but I know what I am hearing and it's VERY nice.

I can highly recommend the combination but I don't know how durable the PPP is since I had to send it back to PS Audio for repairs after about a year of use. I believe this is why they came out with the newer P5 and P10 reconditioners. Either way, PS Audio has been nothing but great with their customer service and I appreciate them being able to fix my unit free of charge without even asking when I purchased the unit. This is a good thing. Good customer service is a godsend in the event you need to use it. 

Getting back to the point, if you are interested in the PPP because of its ability to produce perfect, clean, voltage-controllable power but are worried about the fact at it's not using balanced power with a super-low noise floor, then this is where the Equitech comes in and saves the day. PS Audio could not keep the size down and efficiency of the PPP up without losing the balanced output. Fortunately the Equitech solves this problem by allowing the user to plug the 1.5Q into the PPP and achieve the perfect power union. I assume the newer P5 and P10 can come close to this combination but have not had the opportunity to try them as of yet so we will keep you informed as things change. Either way, this power combo is a pleasure to use and really does make a considerable difference.


Associated Equipment for this Review:

  • Von Schweikert VR-5 HSE (Hovland Special Edition) Speakers
  • Quicksilver tubed Linsestage and Monoblocks
  • EE Minimax DAC Bolder Cables Level 1 Modified
  • IBM Laptop with Foobar 2K Digital Audio Source
  • Theta Digital Carmen II CD Transport
  • EE Minimax Phono Stage
  • VPI Scoutmaster Turntable with VPI Zephyr Cartridge
  • YFS Custom Cables & Interconnects
  • YFS Custom Room Treatment
  • Herbies Audio Lab Dampening Devices and Tube Dampers


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