The headphone amplifier market is segmented into multiple price brackets and categories, and one of the most competitive is the broad category of compact AC-powered home-based solid-states. There are many amplifiers in this category, ranging from as little as ~$150 (for ones based on open-source DIY circuits), to as much as almost $1000 or more. The entry-level amps in this category are largely considered to be those falling between $300 and $500 though, and it's in that space where the $429 EC/SS from Eddie Current sits. It faces direct competition from two other amps squarely within its range, the HeadAmp Gilmore Lite v2 (with or without its DPS, $350 and $550 respectively) and Heed Audio's CanAmp ($450). How does it stack up against them? Read on to find out.
Power cord: Signal Cable Silver Resolution Reference
Digital source: Arcam FMJ CD33
Interconnects: Signal Cable Silver Res Analog w/ Eichmann silver bullets, PS Audio xStream Transcendent
Headphones: AKG K701 re-cabled w/ Stefan AudioArt Equinox, Audio-Technica ATH-W5000, Grado RS1 & GS1000, Sennheiser HD650 re-cabled w/ SAA Equinox
Comparison amps: HeadAmp Gilmore Lite v2 w/ DPS, Heed Audio CanAmp (briefly), Singlepower Square Wave
Alison Krauss - So Long So Wrong
Alison Krauss & Robert Plant - Raising Sand
Julie London - Around Midnight
Laika - Good Looking Blues
Massive Attack - Blue Lines
Nikolaus Harnoncourt - Dvorak Symphony No. 7
Porcupine Tree - In Absentia
Thievery Corporation - The Mirror Conspiracy
About the EC/SS
Per its namesake, the EC/SS is Eddie Current's entry-level solid-state amp, designed, as its designer Craig Uthus put it when asked, "as a platform to take advantage of the new op-amps from Analog Devices and others. Because the op-amps are in sockets the amplifier is upgradeable." Current production units use the AD811 op-amp, and when asked why he went with this chip, Craig said this: "There are many great sounding op-amps, more coming out all the time. To my ear the faster amplifiers sound smoother and more musical. The AD811 is a video amplifier and ripping fast. It has good drive on its own, but sounds even better driving a buffer. The EC/SS uses a discrete buffer between the op-amp and headphones. Because the amplifier is DC-coupled, some provision has to be made to cancel any DC offset from the op-amp or buffer. The AD708 is used in a DC servo loop to eliminate any DC voltage at the output. This op-amp is not critical and the most important parameter is the amplifier's VOS which is very low on the 708."
The amp has a 16V DC jack for connection to a wall-wart AC adapter instead of using an IEC inlet, and When asked about this, Craig said that this was by design to isolate the power transformer from the amplifier circuit: "The EC/SS is powered by an external AC transformer. In this case the transformer is a wall wart. The AC from the transformer goes to four Schotky diodes which feed four separate DC shunt regulators. This effectively isolates the transformer from the circuit."
The amplifier's specifications are as follows, which show that it's more ideal for low-impedance, efficient headphones due to a rated power output of up to 3W at 32 Ohms:
- Maximum drive current both channels @ 300 mA
- Max voltage swing with symmetrical clipping at 13 volts peak
- Maximum power into 32 ohms, 3 watts peak
- Maximum power into 300 ohms, 560 mW peak
- Frequency response driving Grado RS-1 / Sennheiser HD650: -0.5 dB @ 1 Hz / 250 kHz
- Output source resistance 0.5 Ohms
Gain on the amp is a default of 5, but can be set to 10 by pulling off the respective pin jacks on the two gain set resistors.
Craig also said that the amp was designed with the Grado RS-1 and Sennheiser HD600 headphones as references, and when asked why, he said it was because "they are a good balance between current drive and voltage drive. If the amplifier does a good job on both cans it will play well on just about any headphone."
Valid reasoning there, and so it was fortunate that I was able to evaluate the amp with the Grado RS-1, but with Sennheiser's HD650 instead of the HD600, along with the Grado GS1000, AKG K701, and Audio-Technica ATH-W5000.
Headphone & Amp Pairings And More
As the EC/SS is designed with the Grado RS-1 in mind, naturally I spent a lot of listening time with that headphone, comparing it with the other amps, to find out if the amp was indeed a better match for it than the other amps.
First of all, the RS-1 headphones can be used with either flat pads or bowl pads (both of which are available through dealers for Grado Labs), and so I tried the amp with both sets of pads to find out which ones worked better with the sound of the amp. The bowl pads were clearly the winner. The RS-1 takes on a flatter, more evened out perception of frequency balance with the bowl pads, compared to the flat pads, which add some thump & swarth to the mid-bass and lower mids and dull treble energy. Naturally the choice of which pads to use on the RS-1 is completely dependent on listener preference, and of course whichever one is chosen highly affects what kind of amp to pair with the headphones. Repeated listening to both sets of pads and comparison with the HeadAmp Gilmore Lite showed that each set of pads clearly went in favor of one of the amps - the flat pads worked better with the Gilmore Lite, and the bowl pads worked better with the EC/SS. This wasn't entirely unexpected - the Gilmore Lite has a bright treble tendency and slight forwardness in the mid-range and hence balances out the perceived sound through the flat pads, while the EC/SS offered a different sound that better complemented the sound through the bowl pads. Despite this discovery I listened to the RS-1 with bowl pads only on the EC/SS and Gilmore Lite, along with the Square Wave, to find out where just the amps differed (instead of trying to alter the sound through the pads).
On Massive Attack's "Daydreaming" from Blue Lines, the Gilmore Lite combo proved to be less than stellar for this track. The soundstage seemed confused, as if layers were unnaturally in front or in back or back-left or front-right. There was a weird diagonal-type effect that threw off the imaging. The EC/SS, on the other hand, conveyed a deep, strong bass impact on the drums, and sounded weightier and thicker. It also gave a heavier intonation on the male vocals and presented an image with a very convincing "you are in the room with the band" effect, allowing everything to sound more surrounding, though not quite as deep on the z-axis. The Square Wave combo was really good too though, as it brought the soundstage the most front and center with a greater portrayal of air. The weight of the drum line was a tad less than on the EC/SS and was less omnipresent and leaner, but on the flip side it sounded deeper and more anchored down. In comparison, the EC/SS just didn't have quite the Square Wave's bass "stopping power," as it wasn't completely clean around the edges and sounded a bit looser with less grip.
On another track, Thievery Corporation's "Samba Tranquille" from The Mirror Conspiracy showed a big difference between the three amps, each with its own strengths and weaknesses. The Gilmore Lite delivered the best overall clarity and speed and most precise capturing of the snap & impact of the main percussion line. It also actually placed the main percussion rhythm towards the back instead of bringing it to the center or front, and it had the deepest soundstage allowing it to convey the most air. The Square Wave went in a different direction and was like a jackhammer on the percussion line, practically sending it flying into the face. It dug down strong and very deep on the bass rhythm too, and actually ended up delivering the most prominent double-bass of the three amps. However, there was some slight delay in the attack, and it seemed as if every instrument moved forward in their soundstage position compared to the Gilmore Lite, so it wasn't very deep. The EC/SS in comparison delivered a great middle-ground between the two other amps, as the positioning of the instruments was between that of the Gilmore Lite and Square Wave, and ultimately the most realistic as well, as the Gilmore Lite seemed to push them away too far and the Square Wave brought them a little too close. There was a very, very realistic sense of space, as if the music was occurring live in an actual room. The double-bass wasn't as prominent as on the Square Wave but there was more texture to it, as it sounded more tactile and realistic and had a greater "feel" to it. Overall the EC/SS was the most natural-sounding of the three amps, and didn't sound effusive or laid back or snappy.
Spinning through some other tracks like AKUS's "The Road Is a Lover" from So Long So Wrong, Alison Krauss' "Rich Woman" from her brand-new CD Raising Sand, Porcupine Tree's "3" from In Absentia, Julie London's "Misty" from Around Midnight, Laika's "Widow's Weed" from Good Looking Blues, and the classical cut of Dvorak's Symphony No. 7 conducted by Nikolaus Harnoncourt, showed that the EC/SS is probably one of the best amps to go with the Grado RS-1. It simply complemented the sound of the headphones perfectly when used with the bowl pads - mid-range was bold and vivid with full natural colors, as the amp carried every sound as if it was a painter with a bucket of rich hues working on his latest masterpiece. Broad, sweeping strokes, with an artful flair, almost as if the amp was the painter's brush itself being carefully and thoughtfully applied. The amp imbued a solid, sweeping mid-range with just the right amount of body without overdoing it, and created a soundstage with focus and realism. Granted it did consistently shrink the size of the soundstage (which ended up being way too obvious on my Arcam FMJ CD33), but on the other hand, it did create a realistic sense of space with proper delineation between walls, that recordings in a room actually sounded like they were in a room, instead of in a large room or auditorium conversely.
And the amp didn't stop sounding good with just the Grado RS-1 either (though it was certainly the most impressive with the RS-1). The gain of 5 proved to be just as useful with the Audio-Technica ATH-W5000, which is 40 Ohms. While a lower gain would have been even more useful for the W5000 for more fine-tuning, the volume pot of the EC/SS still allowed for enough volume control. The W5000 turned out to be more complementary with the Square Wave amp instead as that amp offers even more tonal color and a thicker/heavier mid-range (and deeper & more anchored bass), but the EC/SS was good too, just not at the same level - the body of the mid-range added just enough to balance against the W5000's intrinsic boost of the upper mids, and there was a good amount of tonal coloring too, and no unnecessary boosting of the upper treble either. The W5000 did make it obvious that the Square Wave is a very mid-range focused amp though, more so than the EC/SS, and of course the amount of mid-range emphasis of an amp is a completely preferential thing. In fact, for those who prefer a solid-state amp to actually sound like a solid-state and less like like a hybrid or tube amp, the EC/SS is more solid-statey than the Square Wave, as it sounded more halfway between the stereotypical solid-state and hybrid sounds, whereas the Square Wave is much closer to that of a hybrid sound, maybe even a little past to approach the tube sound.
The EC/SS also worked well with the Sennheiser HD650, better than the Square Wave, not as good as the Gilmore Lite. The HD650's intrinsic sound is a bit slow & sluggish with a partially heavy mid-bass, a warm mid-range, and some relaxed treble energy, making it pair best with the Gilmore Lite, which adds some much-needed speed, tightening of the mid-bass, and boosting of the treble. When paired with the Gilmore Lite, the HD650 simply sounded the most brilliant, the most detailed, and the most open. With the EC/SS, it sounded less brilliant, less detailed, less open - and hence, less complementary. The amp designer's use of the HD600 instead is well-founded, as its sound is much more suited to that headphone instead of the HD650.
The EC/SS also sounded ok with the AKG K701, but unfortunately most of its flaws showed up on the K701. The amp did add some body and fullness to the sound of the K701, but aside from that, it was barely a complementary match, as its sound strikingly recalled the effects of the EarMax Anniversary tube amp which I previously reviewed. Decays were nicely long and full on the EC/SS, but the K701 revealed a lot of sonic disparities that made it a bad pairing - there was an imparted slowness to the attack (there was a distinct lack of timing & precision on AKUS's "Little Liza Jones" on So Long So Wrong for example), loss of detail, a lack of control in the low bass, and as already mentioned above, a compacted soundstage - and on the K701 this was the most noticeable, as of the headphones I used it has the biggest soundstage. True the amp did deliver a smaller, well-defined, natural, & realistic soundstage, but this was a downright detraction, very noticeable on the K701 and Arcam FMJ CD33 - not desirable at all for either this CD player or these headphones. And the amp's loss of detail was also noticeable on the K701 - it failed to pick up some of the subtle, buried layers of Laika's "Widow's Weed" and fuzzed over others. It just didn't have the ear-popping clarity of the Gilmore Lite amp, and it quickly became obvious the Gilmore Lite was the far more detailed amp due to faster tracking and a better ability to split the layers.
As for the Grado GS1000, the EC/SS wasn't an ideal amp for it at all. Though the amp is technically capable of putting out enough power for the headphones, it really did nothing sonically for them, and it didn't push enough mid-range to combat the recessed mid-range of the headphones. The Gilmore Lite was even worse for the headphones as it made the mid-range sound even more recessed, and it was borderline sibilant too. The Square Wave, however, was a big step in the right direction for the headphones with its big mid-range and bass emphasis, and its technical specs are likely enough for the headphones too as its circuit has been confirmed to be discrete and MOSFET-based, with high-current output ability (a formal spec list for the Square Wave has not been released).
Versus the Gilmore Lite & CanAmp
As described above, the EC/SS and Gilmore Lite turned out to be very different from each other, with the former having the warmer mid-range, and the latter being faster and more detailed. The EC/SS consistently caught less soundstage air and downsized it at the same time, leading it to sound almost suffocated in comparison. It was constricted, less breathing room, less air around the instruments - essentially, less spatial. It did convey more body and fullness though and didn't sound thin as the Gilmore Lite tends to do. Natural-sounding, compared to the Gilmore Lite which seemed more on the side of cold-sounding. However, lest that give the wrong idea, this was much more an issue of the EC/SS being the less transparent amp, as the Arcam FMJ CD33 is cold-sounding itself (those familiar with Arcam's house sound should be familiar with this), so if the final sound to a headphone sounds warmer on another amp compared to the Gilmore Lite, obviously that means the amp is adding it.
Likewise, the Heed Audio CanAmp, which uses Texas Instruments' NE5532 op-amp, was also very different from the EC/SS, as it had much more in common with the Singlepower Square Wave. The most notable difference in the CanAmp was that it simply had a much more powerful sound, with more bass and mid-bass quantity, as well as even more mid-range presence. It was nearly equivalent to the Square Wave in this aspect, as those two amps both sounded heavy and weighted, well able to convey inner power and force. The CanAmp clearly eclipsed the EC/SS in terms of fullness & body, almost to the point of borderline thick. This made it sound less agile and slower, and in fact was the least speedy of the amps, as it nearly trudged through complex bass rhythms. The main advantage of the CanAmp seemed to be its powerful sound, as well as its very high gain of 11. True to this gain setting it more than easily drove the K701 and HD650, and other headphone listeners have reported that it's also well able to drive >300 Ohm headphones like the 400-Ohm AKG K340.
A few points have to be taken off for some technical issues with the EC/SS. First, it's not a silent amp, as all the headphones I used it with were able to pick up a hiss/static noise on it as I turned up the volume to max. Normally an amp should maintain a silent background at all volume levels, but the EC/SS did not - and the noise it emitted as it was turned up suggests that it shouldn't be used for headphones beyond 300 Ohms. Granted, the point at which the hiss/static was audible was pretty high on the volume knob, higher than necessary for any <300 Ohm headphone (past the 12 o'clock tickmark), but noise on an amp at any volume setting is not a good sign and very unsettling.
Second, the amp lacks a power-indicator LED, and the power switch is on the back, so it's impossible to tell whether the amp is on by looking at the front. It's an inconvenience, and there could easily be scenarios in which the amp might be accidentally turned on or off.
Finally, the RCA input jacks of the amp aren't typical flat-plated Neutrik-type jacks, as there's a slight bevel at the very end of them. Most interconnect RCA connectors will work fine on these - the Neutrik-grade connectors of some Radio Shack cables, WBT-style locking connectors of the PS Audio xStream Transcendent RCA, and Eichmann bullets of the Signal Cable Silver Res Analog all worked fine with it. However, the WBT-0102 of the VH Audio Spectrum Ag did NOT work ok, and those cables were a big hassle to both plug in and unplug. Inserting them required actual force & pushing, and in order to avoid damage to the connector when removing them, I had to grab the entire connector housing with my hand and pull them out that way. So caution is highly advised when using interconnects with WBT-genuine connectors.
As a previous owner of the Grado SR60, SR80, SR225, SR325i, and RS-1, and the AKG K401, K501, and K601, along with the Audio-Technica ATH-A900 and ATH-AD2000, I'd recommend the EC/SS primarily for use with lower-impedance headphones, and would advise against using it with AKG's. It may technically be able to handle the AKG's, but sonically it would not be an ideal amp for them due to their sound - those would benefit more from either very solid-statey sounding amps (K401 & K601), or tubey-sounding amps (K501). The mid-range and soundstage-focused sound of the EC/SS makes it best paired with the RS-1 and the bright-sounding SR60, SR80, and SR325/i, along with AT's ATH-A900 (and probably the rest of the ATH-Axx line). (The SR225 is an odd one out of the Grado lot as it's not bright-sounding and benefits more from the Gilmore Lite.)
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