Review: PWX power supply for Black Cube

This review is a preliminary review and evaluation of the PWX power supply that is optional for the Lehmann Audio Black Cube phono preamp. I have spent the last several evenings using the PWX, and wanted to share some initial reactions.

The PWX power supply replaces the standard remote power supply for the Black Cube, and can be retrofitted to all Black Cube models. The unit is 9”x4”x1.75”, and the sturdy metal housing is identical in construction to the Cube’s. One end of the PWX has an IEC connection for the electrical power, and a 4-pin Neutrik connector that links the PWX to the Cube. (If you are interested in seeing a picture of the PWX, look at the ad from HyEnd Audio on page 105 of the June-July issue of TAS.)

The PWX has a much beefier power supply than the stock original. The advertising for the PWX claims a ten-fold increase in voltage over the original power supply unit. The claim seems fully substantiated when one looks inside the housing, which contains a donut-sized (cake donut, not raised), German-made 35 VA toroidal transformer, and two 4500 mFd filter capacitors. The PCB, parts, and assembly reflect the usual high German quality standards. All wiring is heavy-duty, with excellent soldering.

The PWX is available from HyEnd Audio (, the importer, for $245, or $275 if you send your Black Cube to them and have them do the replacement procedure. If you decide to do the work yourself, you must be able to solder the 4-pin Neutrik connector onto the end of the umbilical cord from the Cube. This is not difficult for hobbyists who are good with a soldering iron, but others may prefer to have HyEnd Audio do the soldering. (Contact HyEnd and talk to the owner, Leo Massi. Leo’s a good guy who shipped the PWX to me on my word that I’d mail him a personal check. Trust is such a rare commodity today.)

So, how does the PWX unit “sound” with the Black Cube? To assess the PWX’s contribution to improved sound quality, I listened to a cross-section of music: chamber and orchestral music (LP’s by Reference Recordings); jazz combos and bands (e.g., M&K’s D-to-D LP “For Duke”); blues; folk (the MoFi 200 gram Anadisk pressing of Joan Baez’s “Diamonds and Rust”); and some rock (Creedence; The Doors; Beach Boys; The Eagles; etc).

The advertising for the PWX claims “an incredible improvement that adds dynamics, pace, rhythm, speed, focus, and holography”. Based on my initial listening experiences, the claims may be a bit hyperbolic, but I can attest to a detectable improvement in the sound from my LP’s. The most notable improvement, as one might expect from an enlarged power supply, was in the dynamics, speed, and transients. Bass was tighter and had more “oomph”, and transients such as plucked guitar strings were quicker and had more immediacy. I also had the sense that vocalists were more “in the room”, and there also the feeling of enhanced acoustic space – this may be partially because the background seemed “blacker” and quieter, which allowed vocalists to stand out more.

When conducting critical listening to a new component, one must be careful not to be biased by claims of improved performance. I can say, however, that I heard good, although not dramatic, improvements in the audio quality from my LP’s. The type and level of improvement that I heard are nuances, and it takes an already good audio system to take advantage of this. I think this $250 upgrade is a good investment for people who own Black Cubes, AND who have good sound systems. Anyone who is planning to buy a Black Cube should consider investing the extra money and get the PWX power supply rather than the stock version
Thanks for your nice review of the PWX. Did you notice any more inner detail with the PWX? What cartridge and turntable were you using when testing? What PC did you use on the PWX? (Is the unit highly PC dependent?) What is your system? How long did you let the unit warm up? (I have found the Black Cube needs 6 days of warm up to sound its best). I am eager to compare your results with my own Black Cube once Norbert Lehmann sends me the 4-pin Neutrik plug for the PWX (the unit was shipped accidentally without the plug). I am going to change the cable between PWX and Black Cube to the highest quality wire when I install the plug. A Hungarian company--Heed Audio ( introduced a small two-unit MC/MM phono stage called the Quasar (same "plain black metal" aesthetics, but more parts and a longer signal length) that is the new challenger to the Black Cube. Unfortunately, the price is twice that of the Black Cube SE. I saw the Silver Cube at Frankfurt High End 2001 and it looks very promising. Wonder what sonic improvements this unit has over the Black Cube. What I want from Lehmann is more inner detail, directness, focus, and dynamics.
Hi, Slawney. I'll try to answer all of your questions, but must start with one of my own. What does the abbreviation "PC" stand for? Phone cartridge or power cable? I'm going to assume that you did not "personal computer" .

Now to your questions:
1. Yes, I missed a small amount of inner detail, but that maybe have been because the PWX seems quieter than the stock power supply. I want to be clear, however, that the difference was not great.
2. I used two different cartridges in my testing: a Grado Sonato, and a Shure V15VxMR. Both were mounted in a Rega RB900 arm, which is mounted on a VPI HW-19 Mark 4 turntable.
3. I allowed the PWX power unit to warm up about 6 hours. The Black Cube is the one I've been using for about 18 months.
4. The power cable I used with the PWX power supply is the same cable that came with the original Black Cube power supply. At some point I may upgrade the power cable, but I'm skeptical that it will add anything to this unit because it pulls so little current.
5. My system includes a Bryston SP-1 pre/pro, Bryston 4B-ST and 5B-ST amps, Vandersteen 3A Signature main speakers, Silver Lace and Super Silver interconnects from HomeGrownAudio, power cords from AudioQuest, Kimber 8TC speaker cable, and Monster Power HTS2000 power conditioners.
Sure wish Audiogon would add an "edit" feature for posts after they are made. In my first answer above, I typed the phrase "I missed a small amount of inner detail". I meant to say "I noticed a small amount of additional inner detail". Sorry -- sometimes the brain and the fingers just don't click.
Sdcampbell, thanks, I think you answered all of my questions without knowing that what I meant by PC was "power cord." (Confusing abbreviation, which can also mean "politically correct.") From a sales perspective, it is strange that Lehmann is coming out with an entirely new, and assumedly better phono stage at three or four times the price of the Black Cube SE, so soon after launching the PWX. I hope he offers a friendly upgrade policy when the Silver Cube hits the market.
I upgraded to the PWX on my year and a half old Cube. I found the bass to be firmer and deeper. I had always felt that my Glider was a bit thin in the upper bass. The PWX really fixed that. Image is much improved and on the level of my SACD player. It's nice to at least have the analog and digital front ends image and soundstage equally well. In my system it was worth the money. System:
Table - Rega P25 w/Incognito wiring mod.
Cartridge - Benz-Micro Glider
Phono Pre - Lehmann Cube w/TWX
Preamp - ARC LS-7 w/NOS & Infinicaps
Amp - Krell KSA-100S
Speaker - B&W N805 w/(2)Velodyne subs
Wire - ProSilwayIII & Goertz MI2 Bi-Wire
Happy Listening
I'm just wondering whether PWX will improve the sound from my Black cube which is currently plug to my API PowerWedge 212p digital output?