December 2016


World Premiere Review!
Wells Audio Milo Headphone Amplifier
Mixing up a mean synergy sauce.
Review By Dave Hanson

  Before I reviewed the JPS Labs Abyss AB-1266 ($5,495) earlier this year, designer Joe Skubinski arranged for me to borrow the massive Wells Audio Headtrip amplifier ($6999) to drive his power-hungry headphones during the evaluation. After a short introductory phone call with Jeff Wells, the Headtrip arrived promptly at my doorstep and I was immediately taken by the sound. It seemed that no matter what headphone I plugged into the massive Wells amplifier, they would absolutely light up and sound better than I ever thought they could. With planar magnetic designs especially, the Headtrip was an absolute synergy master.

In the weeks following the review I attended CanJam SoCal 2016, where I was able to meet Jeff Wells in person and have a listen to the prototype of his new amplifier, the Wells Audio Milo ($1699). I was shocked by what I heard. The Milo was somehow able to capture about 95 percent of the flagship Headtrip's magical sound at less than a quarter of the price. I asked Jeff how this was possible.

According to Wells, "The Milo is a derivative of all of my amplifier designs. I tried to distill the product down to only the essentials to achieve my sound, but I removed the extra features, reduced the size of the power supplies, transformer, etc., and made it faster and easier to build, reducing labor. I wanted to bring our sound to those many people who have expressed wanting to own a Wells Audio amplifier, but were previously unable to afford it." His efforts appear to have been a great success. As soon as the Milo arrived, I began putting it through the paces with headphone after headphone, hoping to hear them "light up" with magic synergy the way they did on the Headtrip. To my delight, the Milo delivered in spades, milking every last ounce of performance out of the headphones in my collection.

More Power Than You Can Shake A Stick At
And I can shake one mean stick!
Like its big brothers, the Headtrip and the Enigma ($3699), the Milo offers a boatload of power: up to 18 Watts per channel RMS into 32 Ohms. Per Wells, the intention was not to create a powerful amp, per se, it was actually to reduce the massive output power of the Headtrip and Enigma designs on which it was based. With the Milo, Wells found he was able to reduce the power output by nearly 30% without changing the essential sound characteristics or going back to the drawing board with a completely new design. However, the Milo still offers more than enough power to get maximum headroom on impossible-to-drive headphones like the Abyss AB-1266 and the HiFiMAN HE-6.

But with its powerful 30dB of gain and 18 Watts of power there is a bit of a caveat: sensitivity. With any source over 2 Volts there can be very little play on the volume knob. I found myself listening to most headphones at about 85dB with the knob set around 8:00 on the volume pot. That is not much room for adjustment. While it's a small inconvenience, this could potentially become a more legitimate issue since volume attenuators are not always perfect in terms of channel balance within the first few degrees after zero. You may not want to lean on the Milo to drive your old Denon AH-D7000 with your non-adjustable 3 Volt source.

With most digital audiophile players, however, this is a non-issue. Simply turn down the volume on the software and you are good to go. I set a buffer of 6dB in Amarra for Tidal and paired the Milo with a 2 Volt Metrum Musette, and lo and behold, I had plenty of room to play on the volume dial. In the end, most audiophiles will find this to be an easily forgivable inconvenience, given what the amplifier is able to accomplish sonically. Paired with the Abyss, I found the Milo didn't lose much of the secret sauce that made the Headtrip such an ideal pairing. The delivery was clear, balanced and thunderously dynamic. Listening back-to-back with the Headtrip, I found the flagship offered a greater degree of transparency, more openness and better depth, but for the most part, the Milo's performance was very, very close. It sounded far more like a $1000 difference than a $5300 difference, that's for sure.

Wells credits part of his success in pairing down the Headtrip's essentials for the Milo to his decision to buck the balanced design trend. "I personally believe that there are real advantages to unbalanced over balanced designs. For starters, half the parts count means more money can be allocated for better parts quality," Wells says. "The dynamic range is also greater in an unbalanced design. It almost always sounds more effortless dynamically. Balanced designs have always sounded more ‘electronic' to me. Maybe because the signal is being manipulated by more parts."

In addition to the internals, Wells decided to change the overall design of the Milo to more easily accommodate a small desktop space. Doubling the height of the amplifier, Wells used a rare vertical format to reduce the desktop footprint by 65%. The appearance is certainly unique, I can't think of a single amplifier that is aesthetically similar to the Milo. In person, the amplifier is quite interesting to look at, with its dual heat-sink fins on either side and a semi transparent faceplate that allows you to faintly see the lights and wiring inside the amplifier.

But as unique as the Milo appears to be from a design perspective, it is the sound of this amp that truly sets it apart.

The Beauty Of A Blank Canvas
The Milo's sound is defined by superb levels of neutrality and inner resolution which allow it to act almost as a tonal "blank canvas" for your headphones. By this, I mean the amp provides little to no coloration whatsoever, and in many ways, this is the ideal approach to tone from an amplifier. The Milo performs almost strictly in a support role, adding gobs of power, control and resolution so the headphones themselves can perform to their fullest extent. And boy does it ever work. Sub-bass on the Milo is delivered with reference-level technicality. The clarity and separation from activity in the midbass region is easily the cleanest you will find at this price, even besting my more expensive Cavalli Liquid Crimson ($2,999) reference amplifier by a healthy margin. This was especially apparent when the Milo was paired with the JPS Labs Abyss AB-1266. The Milo allowed me to pick out sub-bass detail in complex passages in a way I've only heard on far, far more expensive amplifiers.

An octave or two higher up the frequency spectrum, the midbass really steals the show. Not only is it speedy and clean, the impact is quite possibly the best I have heard, regardless of price point. Kick drums hammer your eardrums with an absolutely seismic level of impact. Switching to other amplifiers always left me wanting to run back to the unbelievable fun factor that the intoxicatingly punchy Milo offered. The separation from the lower midrange is also superb, never obfuscating the other musical content, despite the savage impact from the percussion.

I found the midrange to be incredibly even and balanced, as you may have guessed already, providing a studio reference-level of neutrality. The sound was very open without the sense of shouty "pinched" strain that often plagues amplifiers with less refined power sections. While it offers a nice sense of ease, there isn't much extra lushness or euphony in the midrange beyond what the headphone provides. This is not necessarily a bad thing, and the amp is certainly not boring in the least, but compared again with the tube-hybrid Liquid Crimson amplifier, the Wells Milo had a somewhat drier sound, whereas the Cavalli offered an extra dose of emotional sweetness on the guitars and vocals.

That considered, I found headphones that do provide a little coloration really, really excel on the Milo. The warm and natural-sounding ZMF Omni ($999, as tested) married superbly with the neutral-sounding Milo, creating a perfect storm of rich musicality and technical precision. Along those same lines, my old HiFiMAN HE-400 and HE-500 both performed beautifully, serving as uniquely hued tints on the Milo's transparent window into the recording. It's almost like you are using the headphones to season the amplifier to taste, rather than using the amplifier to season the headphones.

Up top, the treble is airy, sweet and well controlled. Paired with my Sennheiser HD800, sibilance was essentially absent from good recordings, even at 44.1khz CD quality. Initial transients registered with elite precision and cymbals resonated with excellent clarity and well-defined tone. This is an especially impressive combination of attributes, which demonstrates a high degree of treble refinement from the amplifier.

This leads me to what is perhaps the most impressive attribute of the Wells Milo, its attack and decay properties. If I were to use one word to describe the Milo, it would be "incisive". If I had to describe it in three words, I would call it "really, really incisive". From the initial transient to the last hint of decay, each note is delivered with a clean, sniper-like precision. With gobs of power on tap, even the most difficult starts, stops, macro dynamics and micro dynamics are all just child's play for this amp. The sound is always firmly under control, which helps the music feel very free, easy, open and unrestrained. If you want absolutely effortless accuracy in terms of note delivery, you'll find very few amps that can hang with the Milo.

Imaging is similarly precise, surely aided by the fantastic transient response. Cranking up Neil Peart's famous drum solo from Rush's Moving Pictures classic "Tom Sawyer", I was able to pick out the individual locations of the cymbals in Peart's kit with a stunning degree of accuracy. The soundscape width and height are also quite good, leaving plenty of room for all the sounds to layer in neatly together. The depth is well above average too, relative to other solid state options at the price point. Combined, they form a well-balanced and spacious soundscape, an open stage with a three-dimensional shape that didn't feel like it was off in any one direction.

Overall, this is a very clean and transparent sounding amplifier. Listening to "Quarter Chicken Dark" off of Yo-Yo Ma, Stuart Duncan, Edgar Meyer and Chris Thile's masterful classical/bluegrass mashup "The Goat Rodeo Sessions" on the HD800 put me right inside the recording space with the artists. While the bass can sometimes be a little light on this track, the Milo dug deep into the low end, adding clarity and visceral punch that brought a much greater sense of realism to Edgar Meyer and Yo-Yo Ma's bass and cello performances. The airy, controlled and grain-free treble further enhanced this feeling, removing any sense of a barrier between my ears and the recording space.

Setting A New Benchmark
At $1699, I don't think I have ever encountered an amplifier boasting the level of performance offered by the Milo. In fact, I'm fairly certain one would have to climb up into the neighborhood of $2500 to $3000 to get an amplifier with similar levels of sonic prowess. For owners of hard-to-drive planars like the HE1000, LCD-4 and especially the Abyss AB-1266, the Milo will help you tap into the deep levels of musical dynamism hiding beneath the surface in your flagship orthos. I certainly have not come across a similarly priced option that can unleash the beast within the Abyss quite like the Milo can. What's more, the Milo will help you discover previously unknown levels of performance from mid-priced orthos. Really, do yourself a favor and pick up a used HiFiMAN HE400 for $200 bucks, plug it into the Milo and see what happens. Or break out that old HE500 or LCD-2 that has been sitting in your closet. The Milo will reward you handsomely with better sound than you ever knew your old headphones were capable of.

In terms of value, this is unquestionably one of the very best dollar-for-dollar bargains in all of high-end audio today. The amp just rocks, no two ways about it. If you have hard-to-drive headphones, are looking for a solid state amplifier and it is within range of your budget, the Wells Milo is an easy recommendation.

Additional Equipment Used During This Review
Sennheiser HD800
JPS Labs Abyss AB-1266
ZMF Omni
HiFiMAN HE400
HiFiMAN HE500
HiFiMAN HE-6
HiFiMAN HE1000
ENIGMAcoustics Dharma D-1000
Cavalli Liquid Crimson Amplifier
Wells Audio Headtrip Amplifier
Metrum Acoustics Musette DAC
Audio-GD DAC-19
LampizatOr Level 4 DAC
Chord Mojo
DanaCable Lazuli Headphone Cables
DanaCable Onyx Interconnects
Wireworld Power Cables
Wireworld USB Cables
JRiver Media Center
Amarra for Tidal

Specifications
Type: Solid-state stereo headphone amplifier
Maximum Power Output: 18 Watts per channel @ 32 Ohms
THD+N: 0.025% at full output
SNR: -103dB at full output
Inputs: Unbalanced RCA, with dual 3-pin optional ($200)
Outputs: 6.5mm unbalanced and 4-pin XLR unbalanced
Size: 8" x 7.5" x 9.75" (WxDxH)
Price: $1699

Company Information
Wells Audio
106 Bascom Ct.
Campbell, CA 95008

Voice: (408) 376-0861
Website: www.WellsAudio.com