Qables iQube V1 Headphone Amp & iQube V2 Headphone Amp/DAC (Playback 38)

A Class D Powerhouse from Holland

The Dutch firm Qables isn’t exactly a household word in the U.S., but based on my recent experiences I would company’s iQube V1 headphone amp ($549) and V2 amp/DAC ($699) should help establish the company’s reputation the U.S. in a positive. Let me provide some basic background information on the V1 and V2 to help you gauge whether either of the products might be of interest to you.

The iQube V1 is a very high-quality, portable class D headphone amplifier whose batteries are designed to be charged via a USB cable. Thus, the working assumption is that you will likely travel with a laptop (or a phone that uses a USB-type charger), and that you would prefer not lug around a separate wall-wart type charger just for the amp. Controls and inputs for the amp are simple but effective. On the front panel you’ll find switches for amplifier gain (high or low), amplifier on/off, a control knob for the very high quality Alps volume control, and two pilot lights (one for power on, one to show when the unit is hooked up to a USB power source for charging). On the rear panel, you’ll find a pair of mini-jacks (one for analog input signals, the other for the headphone outputs).

The entire amp is only a bit larger than a deck of playing cards. What words can’t adequately express is how nicely made the iQube V1 really is, sporting a matte silver finish with soft-feel black trim that, to me, seems highly reminiscent of the overall vibe of an old-school Leica camera from Germany.

The iQube V2, in turn, is a slightly larger portable product that combines the V1’s amp section coupled with an onboard USB DAC. Like the V1, the V2 is designed so that it not only receives digital audio data via a USB cable, but also uses USB as its charging source. The beauty of this arrangement is that the V2 meets the following core requirements:

• USB data interface for those times when you listen to digital audio files from your laptop or PC.
• USB power connections, which are very convenient (at least as compared to a wall-wart type charger/power supply).
• A high-quality onboard DAC with a low-jitter USB interface.
• Battery power to handle those situations where you cannot, or do not want to, connect the amp to a USB power/data source.
• An analog input for those times when you listen to music stored on an iPod/iPhone or other personal digital music player.
• A high-quality, high-efficiency amp to power just about any type of headphone you might care to bring on the road with you.
In this review, I’ll focus primarily on the iQube V2, since my comments on the V2’s amplifier section will also serve to describe the identical amplifier section of the V1. As you’ll see in a moment, both products have much to offer in terms of sound quality.

OVERVIEW

Consider this headphone amp/DAC if: you want a beautifully made amp/DAC (or amp only, in the V1’s case) that has found a way to tread that oh-so-fine sonic line between sounding open, airy, and revealing, on the one hand, but natural, full-bodied, and downright gutsy on the other. Also choose the V1 or V2 if you like the idea of portable products that use USB ports as their charging sources.

Look elsewhere if: in the case of the V2, you seek a DAC that can accommodate higher-than-CD-resolution data files (the V2 only accepts digital audio files with up to 16-bit/48 kHz resolution levels, but not higher). But note: on CD-resolution material, the V2 actually sounds better than may higher resolution DAC/Amps we have heard. Finally, look further if you are on a tight budget as the iQube units, which use very high-quality but also quite costly internal parts, are relatively expensive).

Ratings (compared to similarly-priced headphone amp/DACs):

• Tonal Balance: 9
• Clarity: 9
• Dynamics: 9.5
• Flexibility: 7 (doesn’t support high-res data files)
• Value: 8.5

FEATURES

While both iQubes may look simple on the outside, Qables has incorporated very high-quality parts in all the right places on the inside. Highlights (as shown on a manufacturer-supplied features list) include:

• Medical-grade double-layer epoxy circuit boards using HOFC (High Oxygen Free Copper).
• Circuit board designs optimized to enhances signal quality.
• Alps potentiometer.
• Vishay series 036 decoupling capacitors throughout.
• Panasonic stack film capacitors.
• Carbon signal resistors.
• Lumberg I/O connectors.
• Fully RoHS compliant design.
• CNC machined aluminum casing, with rubber touch/feel painted covers.
Apart from the construction highlights listed above, the iQube V1/V2 design also incorporates:
• A high efficiency (90-95%) Class D amplifier.
• (V2 only) A built-in USB receiver and separate DAC
• (V2 only) Tentlabs ultra low jitter clock generator.
• A built-in set of 4x AAA rechargeable batteries (non-user replaceable).
• An 8-fold output buffer for a (near to) load independent output behavior.
• A 4th order feedback loop for minimum distortion.
• A fixed, phase-shifted carrier wave oscillator said to decrease inter-channel distortion.
• An ultra low noise front end that accepts any line level source without the need for impedance matching.
Included accessories, iQube V1:
• 4 rechargeable batteries, factory installed.
• Rubber elastic strap.
• Standard mini-jack to mini-jack cable/
• Metal box with padded interior (looks something like a Euro-spec “cookie tin”)
Included accessories, iQube V2, are as above, but adds:
• Velcro/elastic strap
• Custom Mini-USB/charging cable.