Hifiman EF2A Usb Headphone Amplifier

Yeah, I agree with The Wuss.  I am rather new to the headphone amp universe.  So, don't choose to (or not to) buy baseed on my review alone. 

I listening to the HiFiMAN EF2A through my Grados and a pair of Sony Studio Monitors I use for live music mixing.  The Sonys were instantly revealed as crap for critical listening.  The Grados came to life and quickly taught me what the term "muddy" was all about.  This amp reproduces the upper lows through the lower mids as though they are on top of each other.  These frequencies are fuzzy and sound as if the phones are being asked to play too loud without enough wattage, even at very low volumes.  Turn them down low enough to begin to resolve this issue and you sacrifice balance.  The left can is much louder.

This problem leaves you adjusting, constantly, the gain on the amp as well as the volume on the computer.  Unfortunately, each song is different so the search for the proper balance goes on and on.  But, every now and then, your music player shuffles you to a tune that matches the perfect recording with the correct volume levels and you get perfection!  The soundstage is huge, the highs (although usually bright) pick out the vocals and strings delivering a fleeting glimpse of what you were looking for when you bought this thing.  But, the lucky song ends and then it's back to back to your mixing job.

I am going to stick with it and try some new tubes to see what I can wring from this beauty.  The best comparison I can make is to a super-model stereotype.  Very pretty on the outside, but her personality leaves you wanting.  The more time you spend with her the more frustrated you get, knowing the relationship is doomed almost from the start.  But, you definately want your friends to see her before you trade her in.  (Maybe one of them will want her!)

i bought the ef2a as a dac/amp for my work rig, hoping it would represent a nice step up from the portable dac/amp i was using at the time - the ibasso d4.

immediately out of the box, i was struck by its looks.  its an attractive little unit.

however, after a couple weeks of use, the dac/amp really started revealing its weaknesses. 

first, the dac section of this unit is nothing special.  comparing it with the d4, the d4 is superior, providing more instrument separation, more clarity, and less congestion in the lower mids and upper bass. 

and so i kept the d4 in the chain, and decided to use the ef2a as an amp only.  but, the amp section has problems as well.  the first of these is an unruly amount of gain.  so much gain, in fact, that the volume knob is rendered pretty much useless.  

by way of explanation:  let's say i'm using grado cans.  and i'm listening to mp3 using foobar.  i have my computer volume and foobar's volume set to max, as i should.  i turn on the ef2a, and begin turning up the volume until i am comfortable with the volume level.  the problem is, this volume level doesn't exist on the ef2a.  because comfortable listening level is blown past easily in the region where channel imbalance is still an issue on the volume knob.  and when i say channel imbalance, i mean it.  no signal in one ear until 9 o'clock on the dial.  and then suddenly the channels balance out, with raging volume at 10 o'clock on the dial.

so, what does this leave the listener to do other than lower the volume of the source?  and, as computer-savvy head-fiers know, this doesn't do any favors for the sound quality.

and that is a problem with the function of the amp.  i haven't gotten to the sound yet.  it has a few problems as well.  however, in fairness i haven't tube rolled the unit, so i can't say if some of the weaknesses of the amp can't be overcome with a little more money and effort.  (personally, i didn't feel tuberolling a $170 amp  would be fruitful.)

mid-bass, all the way through lower mids seem somewhat closed-in and congested, and the treble seems a bit brighter than neutral to my ears.

and, the amp doesn't really have a lot of power.  in fact, it's frustrating to me that it tries to disguise its lack of power with gobs of gain.  this makes for a frustrating listening experience, as i'm constantly toying with the volume level in foobar and on the amp to reach a listening level that doesn't seem fatiguing, and doesn't have that strident sound of cans being underpowered. 

in fairness, the ef2a sounds pretty nice with grado sr125 and sr225.  this is, in my opinion, a happy accident of headphone synergy more than anything.  so, if you're willing to cut the volume on your source by half, then the ef2a does play nice with those cans.

and so, overall, it really sounds as if i'm bashing the ef2a.  but, i can't help but expect a little bit more from it.

also, did i mention that the rca inputs are reversed as well?  yep, when feeding the amp from another source, i have to plug in the rca's in backwards to correct this.  however, that's just a problem with my particular unit.  but it's indicative, i think, of what you get when you go this route with hifiman...

a route i won't be taking again.