Solo Ultra-Linear DE

Solo Ultra-Linear Diamond Edition Headphone Amplifier

“It might look fairly simple, but this Diamond Edition headphone amplifier sounds like a real gem” HiFi Choice Nov 6th 2016

Download the HiFi Choice review and you’ll discover it excels in all the things you want to hear.

The Solo Ultra-Linear is supplied with our PSU1 outboard power supply.

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Specification Reviews

The Solo Ultra-Linear lifts the performance of any good music source and quality dynamic headphones.

Graham Slee Solo headphone amplifiers are well-known for their great stereo imaging and musicality, and the Ultra-Linear Diamond Edition (DE) will give you effortless dynamics, a powerful but not boomy sound, and a valvey (tubey) smoothness with detailed clarity.

And It’s A Solid-State Headphone Amplifier!

The Solo Ultra-Linear Diamond Edition (ULDE) headphone amplifier replicates tube amplification, but is solid-state to keep it’s performance for all its long life.

So what about tubes does it replicate? It replicates the most important difference between tubes and solid-state, that tubes give a flatter open-loop frequency response which extends into the mid frequencies, before negative feedback is applied. It means that when it’s applied to keep distortion low, it is true 180° negative feedback, and it gives a wholesome sound which otherwise is sadly lacking in solid-state.

We use our proprietary and well-guarded bandwidth extension technique we call Ultra-Linear which replicates this most desirable of tube characteristics.

The Solo ULDE has a completely redesigned output stage and better noise performance than the earlier Solo UL, which means it will drive a much greater range of high performance over-ear dynamic headphones, and be hiss-free when used with in-ear monitors.

Z-Match Volume Control

Unlike tube amplifiers it works with all common headphone impedances, and its Z-Match impedance ranging volume control takes the place of gain switches, allowing amplifier gain to be fixed so it results in optimum musical performance.

Generous phase and gain margins give it great high-frequency stability under all loading conditions. This coupled with its wide input latitude lets it effortlessly reproduce large musical transients with real clarity.

Excellent power supply filtering and ultra-stable voltage regulation make its power so clean that it depicts the minutest of detail, the nuances – the shades of expression, so your music really communicates with you.

It also results in superb stereo imaging with great separation between performers and instruments, dispensing a believable stereo sound stage.

The Solo ULDE reveals the emotional content of your music and will immerse you in your music without fatigue for hours on end.

Solo ULDE Headphone Amplifier on show with Grado

Chosen by Grado for public audition, the Solo Ultra-Linear DE has demonstrated its commanding control over many of the world’s best dynamic headphones, bringing them to a performance few other headphone amplifiers are capable of at any price.

Upgrade To Ultra-Linear Diamond Edition!

Already a Solo owner?
Have it upgraded with the
Solo Ultra-Linear Diamond Edition upgrade board.


Item Measurement
Headphone impedance range 8 to 2,000 Ohms / 16 to 600 Ohms preferred
Power output (rms, both channels fully driven at 1% THD) 32 Ohms: 140mW/channel; 600 Ohms: 30mW/channel
Input sensitivity (for specified power output into 32 Ohms) 511mV rms
Input impedance 37k Ohms at max volume; 50k Ohms at min volume
Distortion (THD plus noise at 9 o’clock volume control setting (qtr power)) 10Hz-20kHz: better than 0.04%; 10Hz-1kHz: better than 0.02%
Frequency response (±0,-3dB) 10Hz – 35kHz
Output noise (22Hz-22kHz, quasi-peak/un-weighted) -95dB
Channel balance better than 1dB
Crosstalk Left to Right -56dB; Input to Input -68dB
Input selector centre-off position non-shorting; -38dB at max volume with 2V rms input (ref: 1kHz and 10kHz)
Output Stage Bipolar class AB
Supply voltage 24V DC unipolar
Size (approx.) W: 107 x H: 50 x D: 185 (mm) inc. controls

Specifications subject to alteration without notice in keeping with our continuous improvement policy.