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Reviewer: Ryan Clarin
Source: Meridian G07
Headphone amps: Emmeline HR-2, Emmeline Hornet, PS Audio GCHA [on review], Eddie Current EC-01 [on review]
Headphones: Joe Grado HP-1000s, Grado RS-1s, Sennheiser HD600s w/Cardas cable
Cables: BPT IC-SL, BPT L-10, VH Audio Airsine w/ Oyaide Rhodium connectors
Power: BPT PPC outfitted with Oyaide Rhodium duplex outlets
Review Component Retail: As received with various upgrades, $2095 ($599 for stock DeskTop, $499 for Max module, $399 for Max DAC, $199 for stepped attenuator, $399 for Desktop power supply)
The Headroom company has been synonymous with the advancement of headphone listening to numerous headphone nuts for many years. These folks were the first to offer dedicated headphone listening equipment ranging from a wide variety of headphones to amplifiers and headphone accessories. With their success, other companies soon took notice and started dedicating parts of their business to supplying headphone products to consumers as well. Headroom recently revamped and upgraded their entire line of amplifiers, arguably in response to the rapid growth and development of headphone amp manufacturers elsewhere, many of whose products have been reviewed on this site and quite favorably. Ray Samuels Audio, Headamp, SinglePower and Meier Audio are but a few in this new sea of dedicated headphone amp manufacturers. Headroom had a staunch and unchallenged position in the headphone amp category for a while but this rapid growth in headphone amp offerings over the past couple of years has stressed that times and choices are changing, with headphone users enjoying access to far more options than ever before. After hearing about the newly launched line, I inquired about receiving a review sample. Even though it took quite a while to get here -- spanning a couple of months added to which was my moving to the 3rd location in the past year and a half -- I was happy to finally have the amp here and take it through its paces.
I received a Headroom Desktop amp fitted with various upgrades. According to Joe Wojciechowski, engineering manager at Headroom, "the overall circuit topology is op-amp based, with multiple gain stages, local feedback and an IC-based output stage. For a standard desktop amp, the op-amps are the Burr Brown OPA2134 and the output stage is the Intersil HA5000-2 buffer. The circuit is DC-coupled throughout. The passive devices are high-grade metal film resistors and Panasonic PPS film capacitors. The PCB is a four- layer design with full internal planes for power and ground. All signal path routing is on the top layer, with special attention paid to ensuring low noise operation."
My review loaner added an internal DAC and an upgraded amp module also featured in the top-line Max amp, but here at a fraction of its price. This package includes an external power supply that can run up to 6 units, plus a stepped attenuator for superior inter-channel matching. The amp is generous with its inputs, sporting two RCA analogue inputs and a variable output that can turn the amp into a basic preamp. With the DAC option, the unit can accept coaxial, optical and USB inputs and switches between them with a frontal toggle. Digital and analogue are selected by another switch. The front of the amp sports two headphone outputs, ¼ inch and 1/8 inch respectively. A high/medium/low gain provision allows maximum user flexibility with a wide range of headphone impedances and sensitivities.
The unit features discrete and bypassable tone filter and cross-feed options. The tone filter is a brightness control that boosts certain frequencies meant to compensate for the natural warming up of the sound when the cross-feed circuit is activated. Build quality is top-notch, with gently sloping chassis curves that accent very well within a system rack. My only complaint? The headphone jacks extrude a bit from the chassis and aren't flush-mounted with the front panel à la the Emmeline HR-2 or PS Audio GCHA. This creates some friction when swapping out headphones. Minor qualm, I know, but I am a reviewer and supposed to be anal-retentive.
One of my first goals with the Headroom amp was to get a grip on the cross-feed circuit and its overall effect. Headroom was the first company to incorporate such a processor in a commercial unit, signifying their claim to fame when they arrived on the scene. This is an active circuit that provides time delay and amplitude attenuation at preselected frequencies. The output of this circuit is then bled into the opposite channel. The cross-feed attempts to model the effects of the Head Related Transfer Function or HRTF. Simply put, cross-feed allows some of the signal from the left channel to bleed into the right and vice versa. This is meant to simulate the way we hear a natural soundfield from freestanding speakers. For some listeners, headphone listening -- especially with older hard-panned stereo recordings -- can create a disconcerting effect wherein the listener essentially only perceives 3 blobs of sound (left, right, center), thus destroying any sense of a continuous, partially enveloping soundstage.
I have always been a dual-mono guy and feel that headphone listening is an acquired taste that takes time to adjust to. The human brain has the ability to "fill in the blanks" and might be the best -- and free -- audio signal processor we have available. Better headphones tend to do a better job of encompassing frontal space whereas cans inferior in that regard simply play laterally between your ears in what we call the headstage. The audible effect of cross-feed is somewhat frequency-dependent in that lower frequencies benefit much more than higher frequencies. My experimentation with the cross-feed processor in the Headroom was two-fold; 1) to compare the general effect of cross-feed over traditional dual-mono headphone listening, and 2), to compare Headroom's implementation against another commercial solution, in this case inside the Meier Audio HA-2.
The effect generally varies from recording to recording. It should also be noted that cross-feed can create some frequency response aberrations. It is in the signal path when switched on and practically every single aspect of circuit design has an effect. Live, binaural and naturally mic'd recordings benefit very little. Other recordings had a dramatic effect to my ears, however. The first thing noticed was an increase in bass weight. On most recordings, the bass seems primarily in one channel. With the Headroom cross-feed engaged, the bass image shifts somewhat to the center, creating a sense of bass presence slightly in front of the listener which I found pleasing with all my recordings. With higher frequencies like cymbals and hi-hats, the image doesn't shift as much but an overall presence of the sound being in front of you spans across the whole spectrum. This does, however, collapse the headstage a bit as the extreme left and right images turn inwards while the presence is simulated in front. I also noticed that the sound warmed up a bit. The midrange gained more body and presence. Without cross-feed, the Headroom sounded pretty dry and lifeless to my ears especially in the midrange, with transients on percussive attacks harsh and edgy.
With cross-feed, things became more natural not only in the soundstage but also with regards to the timbre of certain instruments. Voices became more textured and liquid and tenor and alto saxophone especially gained a sense of realism. The soundstage benefited considerably and really provided a sense of depth and frontal soundscape I haven't heard before from my dual-mono comrades. It was speaker-like in that I could pinpoint the images in a space in front of me, with this vastness further articulated by the sense of blackness and space between performers. The amp's brightness switch features two levels of high frequency contouring. According to Wojciechowski, "the filter function is indeed formed with an R-C network. It is part of one of the local feedback loop in one stage. When engaged in either setting, the filter provides a boost of 2.5dB. The Filter 1 setting boosts from frequencies of approximately 4kHz to 20kHz and the Filter 2 setting kicks in at 2kHz. The filter is designed to complement the bass boost that can occur with the cross-feed circuit engaged."
I personally preferred to leave the filter off. It does what is says but I didn't care for its effects on any of my recordings. Even with Filter 1 in play, my attention was shifted away from the music by creating an unnaturally bright presentation. Filter 2 even affected the natural timbres of piano and alto saxophone. Female voices took on a nasality, which I found unacceptable. I preferred the sound with cross-feed but sans filter.
|In comparison to the Meier's implementation, I found that one to have less of a sonic effect on the overall sound. It was more subtle and the frequency shifts of the Headroom were less apparent. However, the Headroom processor did a better job at placing the images in a frontal arc, creating layers of depth that weren't present with the Meier. I found the sound of the Headroom more satisfactory with the cross-feed engaged so for the majority of my listening impressions, I kept it on regardless of whether a particular recording benefited a lot or not.
The Headroom DeskTop with upgraded Max Module and DAC was a solid and refined product overall yet certain aspects of its performance demand special notice. The bass was full-bodied, textured and deep, never slow, fat or bloated. Pitch definition here was impeccable and the timbres had a richness to them that varied according to whether it was an upright or electric bass. With upright bass, I could hear the notes reverberate through the body of the instrument and derived the hint of sweetness natural to the instrument in a live setting. The electric bass took on more of an edge just as it should. The HeadRoom was very transparent from recording to recording and dead-on bass accurate on every recording I threw at it.
High-end extension and top octave air seemed somewhat lackluster, however. This became obvious with cymbals, flutes and hard-hitting percussive attacks. With the PS Audio GCHA, cymbals had an airy shimmer that was conveyed with spooky realism to define the snap, pitch and body of drums and percussive instruments. Vigorous drum attacks create brilliant upper harmonics that decay quickly. With the GCHA, that information remained intact. With the Headroom (and without the balancing effect of the filter settings which I found too potent), the lower body of the drum sound came through fine but the really high-pitched snappy spray was missing. Drums accordingly sounded slower, more closed in and overall less realistic, lively and dynamic
A lot of headphone listeners can be divided into 2 categories, bass heads and airheads. Bass heads strive for deep hard-hitting bass whereas airheads strive for transparency, shimmering airy highs and an enveloping sound that features ambience and space. I lean a bit more towards the airhead side of things but not too much because I also enjoy some bass-head tendencies. I would imagine that the HeadRoom will satisfy and fulfill the desires of any hardcore bass heads out there.
Headroom offers an internal DAC for a surcharge. The online literature states that "the stock Desktop DAC is based on the Cirrus CS4398, their top-of-the-line flagship DAC. There is actually not much we can do here to make it sound even better but we give it a shot! The first thing we can do is use the way crazy-expensive Burr-Brown OPA627s in the audio chain of the DAC, which is exactly what we do in the Home DAC. The other thing that can be done is to insert an asynchronous sample-rate converter and do a bit of upsampling and dejittering. That's what we got in the Max DAC: an AD1896 between the digital receiver and the DAC. It takes the incoming digital data, stores it, upsamples it, interpolates it, picks a nice juicy word and then clocks it out right on time."
I found the internal upgraded DAC to be right on par with my Meridian G07. The latter had slightly more air and extension at the extremes and a somewhat sweeter overall texture but only very slightly so. Using the Meridian as transport to feed the Headroom DAC and amp was an incredibly enjoyable combo. I really don't have anything to say other than that I enjoyed the music immensely. Even using my computer as transport through the Headroom's USB port gave up very little if anything to the Meridian-Headroom combo. I was actually quite surprised to hear how good and enjoyable the music was through my computer and generic USB cable. Coupled with the ability to have all my music ripped in lossless format on my hard-drive ready to play at the tip of my trigger finger, this combo showed me that computer audio truly has a future in hi-end head-fi when mated with a superior DAC and able headphone amplifier.
I should also note that all of my impressions thus far were with the Sennheiser HD600s on the Cardas harness. The combination was highly synergistic and the pairing fit like hand-in-glove. I could not say the same for the Grado RS-1s and HP-1000s, however. Those sounded muffled, lacked clarity on top and bass and impact were a bit soft. The magical midrange the Grados are known for sounded recessed and a bit distant. This was in stark contrast to the driving, dynamic, lively and highly musical combo with the Sennheisers. To my ears, it seemed as though the Headroom simply had a hard time supplying the necessary current to drive the low-impedance Grados to a level I was accustomed to with my other solid-state offerings.
The Headroom amp as reviewed clocks in at $2,095. When you upgrade beyond the basic $599 Desktop module, it also means having to purchase the Desktop power supply for $399 (which can power up to 6 Headroom amps). One of the biggest questions to be asked is, what upgrades should you get and which ones get you the most bang for your buck? The $399 DAC upgrade is a no-brainer if you plan on using this amp with your computer. Headroom does offer cheaper DAC upgrade options priced at $249 and $299 respectively, with the major differences being the op-amps. Whatever your budget allows for, I recommend considering the internal DAC option.
As for the module upgrade options, I cannot speak with certainty as I haven't heard the stock desktop module nor the Home module. Subtracting the DAC option, the Desktop with upgraded Max module and power supply costs $1,497. My listening impressions would have me place it pretty much in the same league as the Emmeline HR-2, Meier HA-2 and PS Audio GCHA. What I liked most about the Headroom outside of the DAC was its cross-feed, how it put the bass in front of me and allowed me to feel its presence a bit more, as well as the overall sensation of a frontal soundstage especially with the Sennheiser HD600s. The HR-2 had a bit more punch and texture in the bass and I preferred its midrange due to its tube-like sweetness. I would also give nods to the Meier and PS Audio in regards to top octave air and high frequency extension. I have the Eddie Current EC-01 on hand as well but didn't really make too many comparisons seeing the EC-01 is a single-ended OTL. I will say that the Headroom with cross-feed and HD600s created a soundscape and continuousness that rivaled the EC-01, yet there is something special about tubes when it comes to continuousness especially in soundstage depth.
The best thing about Headroom is that they offer tons of products at various price points that are bound to please many headphone users. They even sell their DAC as a $299 external unit using the same Cirrus chip as implemented in their higher end amps. It should also be noted that the Desktop amp with full Max module and DAC upgrades brings the listener to essentially the same level as their Max amp - but for $1G less. With the DAC and my music library at my fingertips, I had an all-inclusive system based around a computer as transport that could be the cornerstone of a dedicated headphone listening rig for those looking to build one without breaking the bank.
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