Portable Headphone Amplifier Reviews

Prologue
Plucking my Vamp Verza, Galaxy S3, and Sennheiser Momentums out of the gray TSA tray at airport security, I put the cans on my head and stick the rig in my pocket, and carry on listening to music and checking the latest flight updates...it's a miracle, I tell ya.

Convergence is a Bitch
You can have good headphones in one hand, and good music files on a player in the other hand, but getting them to really play well together has been a mighty struggle for the last 20 years.

Historically, the first step was to recognize that portable players didn't have a headphone amplifier section worthy of high quality headphones. Adding a portable headphone amp solved the problem. But convergence isn't easy, and other problems reared their ugly head. Does the player have a line-out, or will I have to use the typically inferior sounding headphone jack to feed the amp? Where can I find a short cable to connect the amp and player without taking up too much space, or will I have to make one? How am I going to attach these gadgets together? Should I use Velcro, rubber bands, find a special bag, or a bit of each? Oh, by the way, with an amp attached, your portable player will no longer fit in your pocket.

Portable amps caught on though, and the problems, for the most part, got solved. There remained an itch that needed scratching, however.

All the new fancy portable digital players could store high quality music, but their digital-to-analog converter (DAC) chips were pretty cheap and not as good sounding as DACs in home gear. Enthusiasts yearned to get at the digits inside the portable players—surely someone would build a portable DAC if portable players had digital outputs. For one brief moment about ten years ago the iRiver iHP-X00 series of portable media players were available that had an optical digital output, and HeadRoom had the Portable Micro Amp that had a DAC with a Toslink input. Portable digital audio was upon us...for about ten seconds, and then the iRiver iHP Digital Audio Players were discontinued.

Then the iPod began its ascent. Its line output was pretty good, and line-out docks (LOD) were everywhere to be found for analog connection to portable amps, but the big breakthrough came when folks like Cypher Labs and Wadia began to figure out how to get digital audio off an iPod. Portable digital audio was off to the races...well, until the iPod became the iPhone.

Strangely, as the iPod morphed its way into the iPhone and iPod Touch, it began to loose its luster as a pure music player. Hard drive space dropped from 160GB to 32GB, and the devices began to sprout wi-fi and cell phone antennas that tended to radiate RF into outboard amps and create noise. Once your portable payer was your phone, one became far less likely to diminish its convenience with a clumsy headphone amplifier strapped to it. Some enthusiasts rebelled and simply exclaimed, "An iPhone and Jerry Harvey JH13s for the WIN!!!"

Personally, I think smartphones make for great music and media players, but making them sound really good and having them remain useful as a phone isn't easy. Can you have audiophile quality sound from a phone that still fits in your pocket? Has anyone managed to solve enough of the convergence problems to actually come up with a viable, hand held, high-end phone? The answer, for the moment, is a somewhat limited yes!

V-Moda Vamp Verza Headphone Amp ($598) and Metallo Case ($101)
While the Verza DAC/amp will work with pretty much any computer or iOS source, the matching Metallo cases are available only for a very limited selection of smartphones: the iPhone 5 and Samsung Galaxy S3. I suppose it's fair to say this isn't the first time mechanical convergence between smartphone and DAC/amp has been achieved. VentureCraft's Go-Dap GD-03 for the iPhone 3 was likely the first, followed shortly thereafter by the Go-Dap Unit 4 for the iPhone 4. Val Kolton, V-Moda's CEO, must have liked the looks and performance of VantureCraft's products as he enlisted them to produce some similar looking externally, but somewhat different internally, products now available under the V-Moda brand: the Vamp for the iPhone 4/4S, and the Vamp Verza for the iPhone 5 and Galaxy S3.

However, the Vamp Verza with Metallo case for the Galaxy S3 is, to the best of my knowledge, the first time a non-iPhone has been mechanically and digitally connected to a third party portable DAC/amp. The S3 supports the USB-on-the-go (USB OTG) standard which allows the phone to act both as a slave (when connected to a computer as an external drive, for example) and as a host (to dish out music to a DAC via USB for example). That USB OTG is being adopted by many portable phone and table device makers is great news for headphone enthusiasts. The bad news is the USB OTG implementation seems to be very random. For example, while the Galaxy S3 will work with the Verza, the Galaxy S4 will not. Argh! (Bangs head against wall.) Here's the current compatibility list for the Verza.

Inside and Out
The V-Moda Vamp Verza accepts only USB or iOS 30-pin and Lightning digital inputs. Two USB connectors are provided; a full-size USB connector for iOS device inputs, and a micro-USB connector for computer and USB OTG devices.

Inside, the Verza has a strongly split personality having two DACs—a Burr-Brown PCM2902 doing computer and USB OTG duties, and an Asahi Kasei Microsystems AKM4353 converting the digits while attached to an iOS device. Specs show the maximum output power of the amp changing from 150mW to 130mW switching from one DAC to the other—likely a result of a slightly different max voltage from these two chips as they share the same 10 Ohm output impedance amplifier. This is one of the few problems I have with this amp: a 10 Ohm output impedance is too high for balanced armature IEMs that are very likely to be used with portables. We'll talk more about that in a bit.

Due to its split-personality, the connectors, indicators, and controls on the outside of the unit are a bit confusing. The two toggles next to the volume knob control the operating modes of the Verza. One toggle selects whether you're using an iOS device or a USB computer/USB OTG device. The other toggle selects the mode when using an iOS device: normal use, battery charging use, or syncing with iTunes.

The volume control knob is nicely protected and also acts to turn the unit on and off with a switch at the far CCW position. The 3.5mm stereo headphone jack next to the volume knob also does double duty as an optical digital output. On the other end of the Verza are a full size USB Jack to connect to an iOS 30-pin or Lightning connector, and a micro-USB jack to connect to computers and Androids. Also on this end is a gain switch—all but the most voltage hungry headphones had plenty of volume for me with gain set to low.

There are two sound mode switches: bass boost, and 3D. Bass boost is only available when using an iOS device. It's a bit tricky to turn on—you have to have the Verza on with an iOS device attached; push the bass boost button; and when the second toggle starts to blink, flip the toggle back and forth once. If the toggle is lit red, bass boost is off; if the toggle is lit green, bass boost is on. The Bass boost seemed a tad too excessive, but was okay. The 3D function works with all inputs...but it's performance is rather like peppermint coated broccoli. A lot of "Wow!" factor, but not very pleasing.

I have the Metallo case for my Galaxy S3, and have not seen the Metallo case for the iPhone 5 so there may be some small differences between their effectiveness as phone cases that I'm not aware of. At first I didn't like the Metallo case much—I typically use an Otterbox Defender for my phones and love the security they provide. The Metallo case doesn't have a built-in screen protector, and button pushing is accomplished through holes in the sides rather than rubber button extenders. It's basically a metal shell you put the phone into, and then close the rear with a sliding backplate. It's a bit of a dirt magnet as it's somewhat open to dust entry. On the other hand, when I open my Otterbox it's nearly as full of dust as the Metallo case, and the Metallo has done a fine job of protecting the phone. Also, believe it or not, I did end up feeling pleased with V-Moda's ABCP (anything but circles and plastic) design esthetic. I ended up quite comfortably enjoying the look, feel, and usefulness of the Metallo case.

So far, the description I've given of the Verza and Metallo is pretty ordinary, but the import of this product is not in its particulars. The importance of this product is in the converged user experience, and if you'll flip the page, we'll talk about that.