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February / March 2010
Superior Audio Equipment Review


North American Premiere
Pass Laboratories XP-15 Phono Preamplifier
I forgot about this phono preamplifier and enjoyed the music.
Review By Tom Lyle


  The XP-15 is the successor to Pass Labs’ venerable Xono phono ‘stage, the Xono being a two-box affair, the new XP-15 is a single chassis unit. Pass Labs claims that the XP-15 improves upon the Xono's design by “lowering noise, having greater resolution, and bass control”. These are mighty strong claims given that legions of Xono fans swore that the Xono was the greatest solid-state phono preamplifier that ever was created. But there is no question that many will forget the old unit when they hear this new issue, not to mention the benefit of the newer XP-15 taking up less rack space with its smaller, yet extremely attractive, superbly constructed cabinet.

Pass Laboratories XP-15 Phono Preamplifier

The Pass Labs XP-15 front panel includes nothing but its sculpted silver aluminum face plate with a blue LED in the center that indicates that the unit is powered. And since Pass recommends that the unit remain powered unless it is not going to be used for an extended period of time, this unobtrusive indicator light remained a constant throughout the review period. The rear panel includes both balanced RCA and unbalanced XLR inputs and outputs, a five-way binding post for the tonearm's ground cable, and an IEC power output jack for the XP-15's removable AC cord. Two pairs of DIP switches control the selectable cartridge gain and loading. There are three gain settings: 56, 66, and 76 dB, and the cartridge loading can be adjusted from the DIP switches from only a couple of Ohms to 47 kOhms, with a parallel capacitance from 100 pF to 750 pF. The flexibility of the XP-15 is, as the manual states, “likely sufficient to cover the needs of all but the most obscure cartridge”. I agree. One more thing: the manual that accompanies the XP-15 is one of the most informative, and more importantly -- comprehensible -- that I have ever read.


The XP-15, says Pass Labs, has a very accurate RIAA equalization curve of more than one-tenth of a decibel over 10 octaves that does not vary with a change of gain or cartridge loading. It was designed to produce as little noise as possible relative to its high-gain structure, and Pass Labs met their goal by it delivering more than 0.5 Volt of line-level signal output with a phono cartridge of 0.08 mv. Of course there are many more design attributes to the XP-15 than there is space to illustrate here (I implore one to explore Pass Lab's excellent website), but the reputation of both Nelson Pass and Pass Laboratories precedes it, and the experience that they have accumulated over the years producing their celebrated components, the Xono included, has been inherited by this very important link in the analog chain.

The XP-15 was connected to either a tubed Balanced Audio Technology (BAT) VK-3iX or Acousticbuoy Scorpion, or a solid-state Burson Audio PPE-160 preamplifier. Most of the time I used a Krell KAV-250a power amp, but I also spent some time with an Emotiva XPA-2 in the system. The speakers were the Sound Lab DynaStat electrostatic/dynamic hybrid assisted by a Velodyne HGS-15b sub. The front end, including the phono preamp's power cord as well as the rest of the front-end was hooked up to a PS Audio AC regenerator, with a separate PSA regenerator for the turntable. The Velodyne's power was connected to a Chang Lightspeed power conditioner. The dedicated listening room is treated with Echo Buster acoustic panels, and has two dedicated 15 Ampere lines. As those who are familiar with my current system should know by now, the source that fed the XP-15 was a glossy black Basis Debut V with a LyraHelikon cartridge mounted on a Tri-Planar VII U tonearm.

Pass Laboratories XP-15 Phono PreamplifierFor the majority of the review I used the aforementioned Lyra Helikon with an output of 0.5 mV with the XP-15's gain set at 66 dB. I tried not to drive myself (too) crazy by obsessing over impedance settings, but used the fairly standard 47 kOhms for the first few weeks the Pass was in the system, ignoring the manual's recommendation that I start with the 100 Ohm setting. Ultimately I relented, because 100 Ohms was not only more revealing, but and had greater extension at the frequency extremes. Not only that, it made real instruments sound more like real instruments. But no matter what setting I tried, it was difficult to "ruin" the sound with this phono preamp installed as long as I stayed within the settings that were recommended for most MC cartridges with its output. I tried my using my standby van den Hul MC-One Special cartridge for a while, with its output of slightly higher 0.65 mv, and it seemed to appreciated the XP-15 being set to 47k Ohm a bit more than the 100 Ohm setting, but like most pieces of equipment with variable settings I found that listening to music much more enjoyable than obsessing about such things. Now that I've bored you with these set-up notes, I'll rave further about the XP-15's magnificent sound.


The Pleasure
The Pass Laboratories XP-15 is the best solid-state phono preamplifier I've ever had the pleasure of auditioning in my system. Compared to the very best tube phono preamps, I guess there is a little bit of loss of bloom that is exhibited in the midrange. I said "I guess", because the best modern tube units posses this characteristic without any of the tube truisms of old, such as a loss in frequency extension at both ends of the sound spectrum. But these new-and-improved valve components still seem to impart upon the upper treble a natural sweetness that makes all vinyl come alive beyond the point of just the fact that one is listening to the best that analog can deliver. It is debatable whether this mid-frequency bloom is in essence a coloration, yet there is no denying that it often adds to the perceived "reality" of a sound or group of sounds, especially when it ends up pushing them further away from a dense recording into the listening room. The good news is that the XP-15 seems to be able to take the best of the sound of tubes (and yes, I mean their glorious midrange), add a slamming, tight deep bass, and shave any lingering trace of euphony, and like the best tube units it seems to be able to breathe life into lowly inanimate sound waves. Even though I am an advocate for all that is vacuum tube when it comes to the high-end, yet when push comes to shove my preference is not for one method of amplification over the other, but to get the best possible sound out of one's source that is technically possible, but at the same time we all like to stay within the bounds of affordability (keeping in mind that "affordable" is a term used by audiophiles that in no way corresponds to the definition listed in most library reference books). The XP-15 delivers.

A perfect example of the above traits can be found on the excellent re-issue pressed by Classic Records of the Mercury Living Presence LP of Prokofiev's Love For Three Oranges and Scythian Suite conducted by Antal Dorati. I've listened to this particular pressing dozens of times since I first got it, so please excuse the cliché, but it was as if I was listening to this record for the first time because so many new details of these rather complex compositions were revealed. At the same time this pressing sounded incredible.. But I not just the clarity of sound, but I was particularly stuck by the Scythian side, where the orchestra swells in the beginning of the piece before it breaks out in its pseudo-Rite of Spring clamor. I'm well aware that Prokofiev was influenced by Stravinsky's groundbreaking composition at this time, but I never really enjoyed Scythian as a genuine Prokofiev piece so much before this. The string sound of the London Symphony Orchestra in its prime is outstanding in every aspect, not only because the string sound is rendered so magnificently by the XP-15, but largely because the XP-15 was able to reveal the sound so excellently captured by the Mercury engineering and production team. If you asked me while this disc was spinning, I would have said that this is surely one of the best Living Presence recordings ever released. During the course of the review period I had the opportunity to listen to all sorts of music, but of course when playing music of real musicians playing real instruments in a real space are the best to judge any piece of equipment, and unless this is the first equipment review you've ever read, you're well aware of this fact -- but when playing a record such as this, where I assume all the participants are no longer with us -- those real musicians are reanimated via this sonic time machine.

It is tough to focus on a particular trait of the XP-15, but I was particularly impressed how it was able to sort out complex recordings, yet it did this while retaining the spark of life that makes music reproduction via vinyl so great. Cecil Taylor's 3 Phasis album on New World Records was a perfect illustration, although I will admit that it is fairly common that many either love or hate his brand of free jazz at first blush. When I saw him play live in the late 1990s I sort of enjoyed it, even though much of the sound just washed right over me (and probably over about half the audience that didn't stick around for the second half of the show). But repeated listenings to his recordings not only led to a greater understanding and appreciation of the music, but also to the increased intelligibility of his message. Even if you aren't a fan, please bear with me for a moment while I describe the utter joy of hearing his piano and the rest of his band reproduced with such tonic exactitude, from the piano's lowest to highest registers and everything in between.

During both side long sections of the single piece it hardly mattered if he was playing one of his many unaccompanied passages or underneath the six-piece band's complexus. His thematic figures, daring acrobatics, chord clusters, multiple citations, and percussive lineament were all in full sonic view. The sound of the alto sax of Mr. Taylor's long time partner in crime Jimmy Lyon's had a crispness and naturally hooty blare, and it was never carried away by the undercurrent of the rest of the band. The cymbals on Ronald Shannon Jackson's kit had a lifelike shimmer that cut through the fray, and even though cymbals might not be the first thing that comes to mind as an instrument that might not get lost in a mix, it was almost as important that the sound did not unnaturally stand out. Raphe Malik's trumpet, Ramsey Ameen's violin, and Sirone's bass also didn't find themselves unnaturally highlighted or buried, and sounded as believable as any non-audiophile pressing had the right to. The rather high level of surface noise of the most likely not-so-virgin vinyl was a bit distracting during the quieter passages, but never spoiled the performance because it was kept separate from the music in a distinct field of the huge soundstage.

Even though I said that it was tough to select a distinct trait of the XP-15 that made it so great, if I had to choose it would possibly be its organic flavor -- however, since food analogies might not fully describe a piece of audio equipment, I'll rephrase that and just say that its excellent transient response, natural portrayal of instrument textures, expansive yet appropriately scaled soundstage, tight and deep bass response, modern tube-like midrange qualities, glistening highs, solid bass, and excellent separation of instruments and sounds -- did I leave anything out? -- all without ever drawing attention to the gear that was performing the task, and fairly priced, made this component one that I will mourn when it is finally returned to Pass Laboratories.


And I Conclude
I can't remember the last time I wrote a review with no negative comments regarding the performance of a piece of equipment being scrutinized -- there is always a nit to pick or two, but in the case of the Pass Laboratories XP-15, I can't think of any negatives. Yet a phono preamplifier, any preamplifier, any component, to be a worthy contender for the inclusion in any system depends upon quite a few things. Of course price is often the one of the greatest concern for the majority of audiophiles, but even if it is not, other factors are very important and include but are not limited to personal taste and of course system matching. In regards to system matching, if one is using a turntable with multiple tonearms or tonearm wands with different cartridges, the XP-15's rear panel controls and only one input might not be the perfect phono preamplifier (and a multi-input XP-15 would cost considerably more, as it should). But if I were forced to purchase a solid-state phono preamplifier for my own system with my own money the Pass Laboratories XP-15 would be at the top of my list. Of course this is only because it fits my system and fits my listening habits more than any other that I've ever heard before. So when I found a setting that worked best for my cartridge with the XP-15, I just forgot about this phono preamplifier and just enjoyed the music. No pun intended.


Type: Solid-state phono preamplifier
Gain: 40 dB @ 1 kHz (MM) max, single ended 
         46 dB @ 1 kHz (MM) max, balanced 
         71 dB @ 1 kHz (MC) max, single ended 
        76 dB @ 1 kHz (MC) max, balanced 
RIAA Response: 20 Hz to 20 kHz (+- 0.1 dB)
Distortion: < .01 % THD @ 1mV MC input < .002 % THD @ 10mV MM input
Maximum Output: 20 volts RMS.
Output Impedance: 300/300 ohms
Input Impedance: 47 K or 1K / 0-650 pF (MM) 5 ohm - 47K ohm moving coil
Unweighted Noise: -90 dB ref. 10 mV input moving magnet
                            -81 dB ref. 1 mV input moving coil
Dimensions, 17x12x4 (WxDxH in inches) 
Shipping Weight: 25 lbs. 
Price: $3800


Company Information
Pass Laboratories
13395 New Airport Road
Suite G
Auburn, CA 95602

Voice: (530) 878-5350
Fax: (530) 367-2193
E-mail: info@passlabs.com
Website: www.PassLabs.com













































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