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Pass Labs XP-10 Preamplifier Review

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Pass Labs XP10 PreamplifierPublisher’s Note: This Review is first published in the Offiical Directory of the 2nd (2011) California Audio show.

Introduction

Pass Labs has been on quite a successful journey with their ‘X” and ‘XA’ Series power amplifiers. Much the same can be said for their linestage preamplifiers. On the heels of completing my review of the superb Pass Labs X350.5 power amplifier, I was asked to provide insight regarding Pass Labs’ entry level linestage, the XP-10. Of course, the term “entry level” in the Pass Labs universe does not exactly mean low cost mid-fi. We’re talking about a fully fleshed out high-end solid-state preamplifier with an MSRP of circa $5,250. The XP series of preamplifiers are the latest generation of line stages which supersede the phenomenally successful and critically-acclaimed “X” Series preamplifiers.

It is important to note that my main system has had only vacuum tube- based line stages for the long-term since the mid-1980s. During that time, several solid-state units have “visited” but none have actually stayed very long. So, switching over to what would amount to be an all-solid state system for any length of time, is quite a significant change from my norm. That said, the change was not as dramatic as I once feared. More on that in the body of this review.

Getting Started

The entry level Pass Labs XP-10 is a scaled down version of the top-of-the-line XP-20. The two differ mainly in input and output connectivity capabilities as well as the former having a smaller power supply. As such, the XP-10 is a preamplifier housed in a single chassis. The bigger brother, XP-20, has a second chassis to house the beefier power supply.

The XP-10 has a very generous complement of five inputs, two balanced and three single-ended. On the output side of the equation, the flexibility is a bit less generous with two outputs, one balanced and one single-ended. This necessitated significant change to my system connectivity for purposes of this review.

The Pass Labs XP-10’s ergonomics are simple and elegant. The front panel is dominated by a large, bright, and easy-to-read fluorescent display, a mode selector button for the single large multi-purpose knob which serves as manual volume control, mode selector, and balance control, input selector switches, and a mute button. As is typical these days, the well-laid out remote also provides all of this functionality from the comfort of your listening chair.

Inserting the XP-10 into my system for a quick listen and then for break-in turned out to be a bit of an issue. I typically utilize two sets of single-ended outputs from the linestage, one set to the power amplifier and another to the subwoofers. The XP-10 provides facilities for just a single output using single-ended connectivity. Fortunately, I happened to have a set of the TRS Audio Pure Note Designer Series balanced interconnects (more about these babies in a future review) in for evaluation and nearly broken in. I was therefore able to utilize these for connectivity to the main power amplifier(s), and the single-ended outputs for the subwoofers. Rounding out the connectivity duties were the superb Aural Symphonics Magic Gem v2t powercord, and the Aural Symphonics Chronos single ended interconnects for the subwoofers and digital input source.

Speaking of Installation and Break-in….

Fresh out of the box, the XP-10 exhibited the sonic neutrality that Pass Labs amplifiers are famous for. I noted that as is typical of a new piece of electronics, the soundstage was somewhat narrowed and foreshortened and the deepest bass was noticeably muted. Using my favorite break-in CD, I played the XP-10 continuously for 2 weeks, roughly 300 hours. This may sound like overkill but past experiences dictate that some pieces of equipment need at least that long in order to reach their optimum. I also used this as opportunity to complete the break-in of the TRS Audio Pure Note Designer Series balanced interconnects.

After the break-in period I sat for a first long listening session on a Sunday afternoon as is customary. This necessitated swapping back to the superb Aural Symphonics Chronos interconnect, since the TRS Audio Pure Note cables introduced a second variable that would have been inappropriate for critical evaluation of the Pass Labs XP-10 line-stage amplifier. A quick listen to a personal favorite for these type of initial sessions, the original MFSL LP of Rickie Lee Jones’ debut album, particularly the cut “Last Chance Texaco,” I noted a slight haze in the low-end in the otherwise pristine sonics of the XP-10. Having had the pleasure many years ago of obtaining several copies of this LP, I was able to replay the cut without detriment to the LP’s and swap a couple of alternate self-styled platforms of various materials. In the case of this line-stage, 3/8” Delrin slab did the trick and hit a certain sweet spot of tone in the brushes on the track “Easy Money” that I did not note as lacking, until they simply improved in focus and clarity with this material as a footer.

The Sound…in the beginning

In my first extended listening session, I configured the same as in the prior review of the Pass Labs X350.5. This included the Pass Labs X350.5 power amplifier, Pass Labs XP-10 line Stage, Aural Symphonics Chronos, Aural Symphonics Purple v3, Aural Symphonics MagicGem v2t’s throughout. I was therefore left with the simple swap of the Pass Labs XP-10 and my reference Conrad Johnson CT-5.

As I hinted in the introduction, the preamplifier swap proved to be quite lacking in drama. Listening to my battery of CD’s and vinyl, I could not help but noticed the different flavors that were at play here. The Pass Labs XP-10 has a sweet presentation in the midrange and highs without any hint of grain. The upper bass and lower midrange are particularly free of any aberrations and really shone through on my full range electrostatic panels with startling clarity and focus of male vocals.

Equally as compelling was the total lack of distortion or strain on challenging female vocals. As I mentioned in my introduction, the XP-10 is certainly not your garden variety entry-level product. Most notable is the fact that high frequency information such as bells, chimes, and cymbals, are reproduced with the sort of sweetness, liquidity, and richness of tone that I usually find so endearing with vacuum tubes. This indeed was a pleasant surprise.

In the area of focus and image rendering, the XP-10 acquits itself admirably. What is truly unique about the XP-10 is that whereas typically solid-state preamplifiers I have come across in this price range, fall flat when it comes to pace, rhythm, and timing; such was not so with the Pass. The transients are not rounded, nor smoothed out to the point of sounding compressed. In fact this is the main reason why it was such an easy and nearly transparent swap with the Conrad Johnson. The Pass Labs XP-10 really nails dynamic expression.

That said, this is where similarities end and differences begin to emerge. The Pass Labs XP-10 has a vanishingly low noise floor. In fact, the preamplifier is absolutely dead silent both in terms of sonic attributes as well as in function. Gliding up and down the volume ladder with the Pass Labs XP-10 is an absolute joy. It is dead silent in lieu of the very familiar loud CLACK-CLACK-CLACK-CLACK of the Conrad Johnson’s internal relays that activate volume changes via a series of resistor activations and de-activations.

However, even with the astonishingly quiet background and low noise floor, the XP-10 does not attain the soundstage depth, detail, and clarity of my reference preamplifier. Indeed, as my written notes of the first few critical listening sessions revealed, the unmistakable “live” quality that some recordings portray in my system was lessened to some degree due to the slightly constrained soundstage.

Bass impact remained noticeably impressive in the now subwoofer-less system and is indeed a testament to the superb Pass Labs X350.5 stereo power amplifier in the way it manages to extract real bass from my full range electrostatics. However, the Pass Labs XP-10 was clearly a bit of a lightweight in the extreme bottom-end, perhaps even more so than my reference Conrad Johnson.

A “Balanced” View

After several listening sessions and feeling well-versed at the sonic signature of the Pass Labs XP-10, I once again turned to fully balanced operation. I swapped the amplification interconnects from the single-ended Aural Symphonics Chronos to the Balanced TRS Audio Pure Note Designer Series interconnects. The differences were not subtle.

In some ways, the XP-10 seemed to bathe its sound in a richer tonal palette. To me, the cable change resulted in improvements in nearly every respect; cymbals and bells became sweeter and with improved image rendering, drums and assorted other percussion instruments seemed to come alive with explosive dynamics, clarity, and focus, in much the same way as the Conrad Johnson. Indeed, the subjective “audiophile”- type differences narrowed to the point where all that was left were the two distinctly different flavors of their respective “house” sounds. All it took, in both cases, were sets of cables that completely eclipse the cost of each respective preamplifier!

Summing It All Up

The Pass Labs is a solidly built, ergonomically wonderful, and well-executed high-end audio preamplifier. It is dead-on neutral and its “house sound” is that it actually contributes no sound of its own. In some areas, most notably in the lowest bass and to a lesser extent in micro dynamics, there are subjective errors of omission. However, the bass it does deliver is astoundingly clean and controlled. The fact that it held its own so remarkably well when compared to my reference preamplifier earns it a very generous helping of respect from me.

It is also clear that when run in balanced mode, the synergy between the Pass Labs preamplifier and Pass Labs amplifier is undeniable and it brought the total package in terms of performance a very long way toward achieving truly exemplary performance. However, therein lies the rub. Can these performance levels be mimicked with cables that do not completely eclipse the cost of this preamplifier? Perhaps that is a question that needn’t be asked since it probably holds true for most any audiophile component system.

Indeed, with balanced cables in place and the subwoofers back in action, the total resulting system is as subjectively enjoyable as any system I have assembled in this room. Once you achieve these levels of performance, personal tastes really rule the day. In the purest geeky audiophile sense, the Pass Labs XP-10 and the Conrad Johnson CT-5 are extremely close in the performance they deliver. However, their approach to the sonic truth couldn’t be more different. I can easily see myself actually choosing either configuration depending on the source material I wish to listen to.

Kudos to Pass Labs for building a preamplifier that achieves a level of performance that reaches well above its price

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