[ Intro ]
If headphones are generally overlooked when it comes to hi-fi audio, and dedicated headphone amplifiers even moreso, then *portable* headphone amps have been one of the most largely unseen trends of the last several years. After all, in this hobby, usually the bigger the better, right? Indeed, a lot of even self-professed headphiles often don't take portable amps very seriously.
That said, one of the most recent trends in headphone hi-fi has been the emergence of a collective "threat," if you will, of a new wave of portable amps. Not that these necessarily compete with desktop or home amps, but the latest portable amps are starting to fill a void where previously almost nothing existed, offering audiophile-grade sound for portable sources, be they portable CD players or today's digital audio players, like the iPod for example. Just about everyone wants to take their music with them, and what better way to keep it hi-fi than with a portable amp? Of course, if it weren't for line-out jacks and line-out docks, external amps would be near useless, but thankfully nearly every portable source today offers some kind of line-out option.
Reviewed today is a portable amp from Xenos Audio Systems, a subsidiary of the Ontario, Canada-based ATP Systems, and a vendor that made a small splash just a couple years ago with its original portable amp, the 0HA-REP. Xenos has made some strides since then, and just last month introduced its latest model, the 1HA-EPC. Priced at $229, it falls closer to the upper-end segment of portable amps, as the most expensive portable amps get close to $400. Can it hang with its competition in that price bracket? Read on for the answer.
[ Associated Equipment ]
Sources: Arcam DiVA CD73, Cambridge Audio Azur 640C V2
Power cord: Signal Cable Magic Power Digital Reference on Arcam, Iron Lung Jellyfish on Cambridge
Interconnect: Signal Cable SilverMini
Headphones: AKG K701 and K601, Audio-Technica ATH-AD2000 and ATH-ES7, Grado SR225
Comparison Amps: HeadAmp AE-1, Gilmore Lite v2 w/ DPS, and GS-1
Retail price of review component: $229.99
Obviously, I used the amp in a system for which it is not designed since it's more for use with portable sources and portable headphones. So the big question mark for me was, could it pull double-duty as a home-based amp?
[ Test CDs ]
Alison Krauss - Now That I've Found You
Jewel - Spirit
Howard Shore - The Lord of the Rings: The Return of the King [OST]
Hybrid - I Choose Noise
Massive Attack - Mezzanine
Norah Jones - Not Too Late
Neotropic - Mr. Brubaker's Strawberry Alarm Clock
Renee Fleming - Thais (Massenet, 1894)
[ Physical Aspects/Features ]
As far as portable amps in general go, the X1HA-EPC is a bit larger than most, as most tend to be not much larger than a full deck of playing cards. It's not pocket-sized (few amps are truly pocket-size anyway) but it's not "huge" either - think of it as "hand-sized," as it's pretty close to the size of an average human hand and can easily be tightly grasped. It's just the right size to stuff into a carrying bag or
backpack or to have stationed next to you on a desk. Desktop operation works very actually, as it's large enough to have heft and won't fly off if you accidentally hit it with something. It comes with 4 stick-on rubber feet to aid with traction that should be installed right away - otherwise the aluminum bottom of the amp will make full contact with whatever surface it's placed on, naturally undesirable if the intended surface is also metal.
True to form for most portable amps, the X1HA-EPC can be powered by either AC adapter or battery. On this amp, the battery is provided in the form of an internal, rechargeable lithium-ion that Xenos claims will run for 16 hours (in my tests it ran for slightly less with the load of the K701). The AC adapter is included with every amp order by default and is said to recharge the battery in 4 hours. Of course, the AC adapter can be left plugged in permanently or simply used to recharge the battery when it gets low (the pilot light blinks as an indicator).
The front panel is compactly designed and gives access to the amp's two unique features, the Stereo Field Simulator (SFS) and gain boost. SFS is essentially a crossfeed toggle - and crossfeed, for those unfamiliar with it, allows signal crosstalk to occur to achieve the illusion of soundstage. This toggle had less than ideal results with the K701, K601, and ATH-AD2000 due to their innate soundstage abilities, as the image seemed to collapse and flatten (a lot of the airiness was sucked out as well), but worked better with the Grado SR225 and ATH-ES7, helping to add some dimension in the 2D aspect of the image (increased width), but none in the 3D aspect (no depth). Results and preferences with other headphones will vary, of course.
The gain boost feature increases volume swing to 22 dB from 12 dB, though it wasn't essential with any of my headphones, ranging from the 32 Ohm Grado SR225 to the 120 Ohm AKG K601. With the gain boost off, the amp was well able to push the K601 to a loud volume right around the center 12 o'clock position. If I had to guess the position for 250/300 Ohm headphones, I'd say that those would probably call for a 2 o'clock position to attain a loud volume. So even without gain boost the amp could probably easily tackle 300 Ohm headphones - I'd imagine the intention of the toggle was to probably add ability to power 300+ Ohm headphones.
[ Power Output/Sensitivity ]
According to the spec sheets published by Xenos, the amp seems to adjust power output based on the impedance of the headphones plugged into it, doing at most 880 mW for 32 Ohm headphones and scaling back appropriately for increasingly higher-impedance headphones. Based on listening alone I wasn't able to verify this self-adjusting though, so I'll have to take Xenos' word for it.
As already mentioned, I didn't find the gain boost to be essential for my limited set of headphones. Even with low gain, volume shifts on the ATH-AD2000, ATH-ES7, and SR225 seemed a bit excessive - enough leeway was provided for those headphones between moderate and loud levels, but there wasn't enough fine-tuning control for more gradual adjustments. An even lower default gain would have been more useful for these eminently low-impedance headphones.
[ Noise/Background ]
The review unit is a revision on the original model that Xenos released, revised due to initial reports of amp noise, particularly on IEMs (in-ear monitors). Although I don't own any IEMs and couldn't test this reduction of the noise floor, I did plug in the 32 Ohm ATH-ES7 (which uses closed drivers) and turned the volume all the way up - there was no discernable hum or hiss at any point on the dial. However, there were a couple faint "clicks" as the volume knob approached maximum volume, and at full maxed-out volume I did hear buzzing from the AC adapter when it was plugged in. This buzzing was only noticeable with the Signal Cable SilverMini though (which has very thin shielding and is thus susceptible to EMI), and it disappeared when a thicker-gauge Radio Shack-grade IC was installed, but it's still worth noting.
The amp also has a clear, black background both at rest and during music playback, and allows notes to sound as if they're emanating from nowhere. It doesn't approach the level of blackness to be found on higher-end amps though, as it lacks a sense of pure empty space and oblivion, but then who expects that level of performance from a <$500 amp?
[ Soundstage/Imaging ]
Overall imaging on this amp is very well-defined, as it's well able to capture subtle left-right positioning and easily pinpoints & tracks both static and moving layers that shift between channels. It doesn't force any unnatural tendencies on layers moving between channels, simply allowing them to easily flow, but it doesn't provide truly exact, precise control over separation. In other words, I got more of an impression that it lets the layers collide into each other, rather than trying to keep them spaced apart. It was noticeable on music that used multiple concurrent, complicated layers, as it got increasingly difficult to locate individual component sounds by ear, due to loss of distinction. Not that this is a serious fault of course, as it's merely a portable amp, but to my ears it didn't have the ability to peel apart and expose complex mixes. Soundstage width is much better though, as it provides a nice "big picture view" presentation with a convincing sense of left-right space over the stereo field, and this works very nicely for orchestral music in fact, helping to delineate between the instrument sections. Unfortunately, depth isn't defined as well as width, as the amp doesn't provide much of a sense of peering into space along a z-axis. Despite this, the amp still presents a solid soundstage without adding any unnecessary airiness, which is a very good accomplishment for any portable amp.
[ Transparency/Frequency Response ]
If there were any qualms about sound quality in portable amps before, the 1HA-EPC should put most fears to rest. It probably won't win over the most discerning and demanding audiophiles, but it offers very good sound indeed, and the fact that it's from something so portable and less than $500 makes it all the more impressive.
The amp was burned in for ~48 hours before any listening started (Xenos recommends 24 hours so I doubled just to be on the safe side), and upon initial listen, there was no immediately obvious bass or treble emphasis, and no glaring faults on the mid-range either - just crystal clear, fluid, and smooth, nothing lacking about it, it simply conveyed everything with a good, full amount of weight and body. That said, the overall frequency response is a bit mid-range-centric, as bass quantity is noticeably lighter in comparison. While extension of the bass matches the ATH-AD2000's, there's a bit of subtraction from the low/mid-bass, in the specific area that contributes to authority, weight, and undercurrent force. It's as if takes away a chunk of the bass "meat," as test tracks from the Hybrid and Neotropic CDs sounded positively deprived on various low bass phases and tones. Not to imply here that the entire bass region suffers though, as the amp can deliver a moderate amount of impact and power, it's just that it seems to take a slice out of the bass so it no longer sounds full and heavy.
Almost proportionately, treble on the amp is nice and smooth, almost laidback with a lightness to it and can provide detail without sounding aggressive or even remotely crisp or snappy. Easily picks up whinks, tinks, clinks, clatters, etc, along with spatial cues and harmonics. Overall a flat, extended response in this part of the spectrum, very non-offensive to the ears. However, because of the flatness, ultimately it falls short of being able to provide total precision, as it tends to miss the micro-component that's part of the lead (or conversely, the trail) of a note. This is also due to a weak attack that the amp seems to impose, as it seems to have very slight difficulty pushing notes off the "stack" as it were. There's not a whole lot of insistence or energy behind the onset of extremely high and fast notes for example, so it sounds like they're not being completely rendered, and they don't quite jump out in the soundtrack as they should either.
So the amp isn't very transparent on the input signal, as it dulls both low bass and upper treble - almost the converse of the Gilmore Lite v2 w/ DPS, in fact. I'd rate it at about 90% transparent too though since it has roughly the same number of colorations, but on the flip side.
[ System Synergy ]
RCA-mini interconnects are very sparse in my collection as I had only the Signal Cable SilverMini and a Radio Shack grade copper IC, and naturally the amp performed much better with the Signal Cable, which isn't even fully silver either (the core is silver but the plugs are copper), so a statement about possible synergy can't even be made here. It did improve with the Signal Cable of course, most notably in the overall clarity of the sound and refinement over the bass and treble.
It also proved to be somewhat receptive between my two CDPs, but not as much as the other high-end amps in my system as it didn't really capture the nuances of the CDPs. It did reflect their basic frequency response, passing on the extra bass and treble emphasis of the Cambridge, and the warmer, livelier mid-range of the Arcam - but it wasn't really a window into the sound of either CDP, as their sonic virtues simply didn't translate through the amp to the headphones. Naturally, the amp would be much better paired with more budget-minded sources.
As for headphones, since it worked well with every headphone in my system, it would likely work just fine with most single-ended dynamic headphones. Due to its non-offensive sound I imagine it would pair up with just about every brand with varying degrees of preferential synergy - AKG, Beyerdynamic, Sennheiser, Sony, etc. The only issue I'd point out here is that low-impedance headphones are slightly difficult to control with it due to the excessive gain even at the lower setting, so I'd have to advise against Audio-Technica and Grado, as over 90% of the headphones made by both companies have impedance ratings of 40 Ohms or lower.
STEREOMOJO SPECIFIC RECOMMENDATION
If this review sounds a bit overcritical of the Xenos 1HA-EPC, that was on purpose, as my main amp references are the HeadAmp GS-1 and Gilmore Lite v2 w/ DPS (click to read review), which are both AC-powered home amps and easily outclass the Xenos, especially on sound quality alone. That in no way is intended to take anything away from the amp though. On the contrary - I wanted to show how close its sound quality was to the Gilmore Lite - a lot closer than I expected it to be. Despite being outclassed, the unit ended up being better than expected in the "mini-home" role in which I placed it and should be even better when used as a portable. Its combination of features, size, and sound quality make it a great option for that, and its price also happens to make it a great value, too.
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