The industry of high-end audio devices doesn’t lack renowned brands or talented engineers.  The passion and drive for hi-fi sound draw in creative energies and personal ambitions like a magnet.  Given this highly subjective domain, where almost everything can be countered, and in a world dominated by Euro’s four zeros figures, very few personalities can enjoy everyone’s esteem and respect as Pass Labs’ charismatic leader does.

Nelson Pass enjoys this title, earned throughout more than 40 decades of activity, which seems like he’s dedicated his whole life to his passion.  Unusually for an engineer of his level in this industry, Nelson Pass offers substantial support to the DIY community (Do It Yourself).  Most of the schemes used for making the Pass Labs amplifiers are public.  For cheaper models, they are offered at no costs through and Just as unusual and remarkable at the same time is the active support he offers to the passionate.  “Papa” Nelson Pass is very active on sound-enthusiasts forums, contributing with his vast experience to many illustrious accomplishments.

“I bet you thought that getting good Class A performance without a feedback loop was exotic,difficult, and expensive.

 Not if you do it yourself”.  Nelson Pass

This long introduction has a specific purpose, which is putting together a very brief presentation of the reasons why I have a very large amount of respect towards this brand.  Pass Labs is part of an extremely short list of electronics I would integrate in my dream sound system.

Besides the “sentimental” cause, there’s the practical one as well, having had the chance to listen to Pass Labs amplifiers within numerous configurations, in systems which integrated Usher BE-10 speakers but also Focal Grande Utopia, and sources like EMM Labs CDSA SE, or DCS Scarlatti.  This article is dedicated to the most sophisticated Pass Labs audition I’ve ever attended.

 Audition Equipment:

Pass Labs electronics in the sistem:

XA100.5 (18.500 Eur) , Pure A class mono-amp,

X350.5 (13.000 Eur), Class AB stereo amplifier.

XP-30 (18.500 Eur), Top Pass Labs preamplifier, built from 3 separate cases.

X-25 (12.000 Eur), Phono-preamplifier.

The rest of the equipment used was also high-class, brands like Piega, Focal, Martin Logan, Jadis or Simaudio – big names in the audiophile world.
Given the multiple variables within the system, the highlighted sound specs are general features that I’ve observed during the auditions.  For this reason I’ve generally described each speaker model behavior.


The sensation of absolute control that the Pass Labs amplifiers create is overwhelming.  Although they used challenging acoustical enclosures, neither of them has, at any moment, left the impression that they need more.  The dynamism of the amplifiers can be felt from the first harmonies; each speaker effortlessly expressed its character naturally.

The impression the Pass Labs amplifiers left me was similar to that of an athlete winning the race without running at full capacity, aware of their own value and the fact that there’s more that they can do.

During the audition I could enjoy the sound imprint and personality of each speaker individually.  Even though the speakers were firmly steered by the Pass Labs amplifiers, they highlighted the speaker potential without interfering with their personality, or with the sonic signature of each acoustic space individually.  JMR, Piega, Martin Logan or Focal have exposed their acoustic capabilities, each of them offering a unique demonstration.  Preferring one brand to another have had much in common with personal taste or each brand’s philosophy, but I can certainly confirm that I enjoyed all versions within that system.

The control of low-frequency sounds may be the most impressive that I have ever heard in my life.  The most important characteristic of the XA mono-amps, which is also present in a lighter form at the 350.5 amp, is the bass which has an extraordinary attack but also texture.  They send out energy you cannot resist.  The slamming of the drums hits you right in the chest and the strong parts are played with such elegance.

The specific agility of Pass Labs products ensures a particularly fine separation of sounds.  All of the speakers within the test, exhibit a wide scene of instruments with a precision that’s almost surgical.  Undoubtedly helped by an acoustic prepared room, the system created a very credible stereo image, making me forget, at times, where I was really at (an audition room or a live concert).

Playing the transients is one of the most amazing features of Pass Labs amps.  While listening to songs with guitar and an orchestra (like Dire Straits “Ticket to Heaven” or “Where do you think you’re going?”) you can distinctively hear every chord they touch, the perfectly integrated accord, the delimitation between every note. I’ve said it before and I will say it again: For micro details, Dire Straits is pure gold.  If only a quarter of the entire fine music would’ve been recorded at the same quality standards, we would’ve been living in a better world.

Although the audition consisted of a large variety of speakers, which were built using very different solutions, I was able to notice a particular fluidity.  All models had tone balance throughout the frequency spectrum so the sound was never muddled up, confused.  The density of the sound info, supported by excellent sources as well, reaches the listener’s ear in a pleasant way, offering musicality which is hard to define using exact terms, but extremely pleasurable to be felt by your own ears.

 Speakers within system:

 Jean Marie Reynaud – Concorde Supreme:  Top model of the renowned French producer.  That was my first serious interaction with this model so I was fairly impressed with the very energetic bass they were capable of.  Transparent, not aggressive at all, with a sweet sound and a very well virtualized 3D soundstage, the JMRs should enjoy a very careful audience.

 Piega – Coax 90.2:  It’s almost redundant to mention the fact that the Swiss really know how to work their metals, and a speaker built from aluminum used in the aeronautic industry can only be spectacular. Using duralumin translates to thinner internal partitioning, high rigidness, high internal volume comparing to its exterior dimensions.
The ribbon-coaxial technology used for mid and high sounds is responsible for the huge sound resolution.  Piega Coax 90.2 speakers are extremely transparent and detailed when it comes to sound.  The bass is high-top, if we take into account the internal capacity of the speakers, being perfectly controlled and with a very savory texture as well.

 Martin Logan – Summit X:  The electrostatic speakers Martin Logan are well known for being “hard to tame”, but I believe I’ve never heard them perform better than within this Pass Labs amp system.  If in other cases there were aspects that I wasn’t completely satisfied with, this time I gladly found the precision and speed in solving difficult areas that I considered amazing.

Integrating electrostatic panels with the active woofers is a gorgeous success as Summit X now sounds like a whole.  The famous Martin Logan filters really work wonders.  A detail that’s worth mentioning, when talking about Summit X speakers, is that their “sweet-spot” is very much wider than in the case of other models present.  Its large radiant surface really did have a crucial part in this phenomenon.

 Focal Maestro Utopia:  Across time, I’ve had the chance to see Pass Labs amps on the whole Utopia range of products, except the Diablo bookshelves, and the synergy between the two brands is one of the best I ever listened to.  Amplified by Pass Labs, the huge Maestro Utopia emit colossal energy and dynamics.  They create a big scene and it’s very well stretched.  The sound plans are highly delimited in all of the three dimensions.

The “Marriage” between Maestro Utopia and Pass Labs mono amps XA100.5 is an explosive one, since the bass is so deep and energetic; it hits your chest just like in a live concert and gives you the sensation that the artists are right over there, in front of you.



This eminently positive presentation is pretty subjective, sentimental but perfectly justifiable.  Without a doubt, when it comes to high-end equipment, with stratospheric prices, there are real competitors; electronics that can compete in many ways with Pass Labs but for me the image, the passion of the man behind the brand and, not lastly, “Papa” Nelson’s sound philosophy are very hard to replace.

I strongly recommend that, at least once in a lifetime, you listen to a well-clot Pass Labs amp-based system, and you’ll surely benefit of one of the most solid sound marks within the whole audiophile phenomenon.

 And because nobody’s perfect…:

The selling prices for these pieces are not accessible to everyone.  Their “Gigantic” design makes them hard to accept by the feminine side of the family; the A class models run at pretty high temperatures and their exterior dimensions require a specially designed room, or at least major changes made to the audition space. Nothing is perfect, not even Pass Labs.




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