Hello wonderful readers! This review marks the first in a change of approach here at Passion for Sound. I’m moving the bulk of my review detail into the video reviews over on YouTube, but will continue to post the videos here along with a summary TL;DW (too long, didn’t watch) version here. Thanks as always for your readership and support.
If you want to join Massdrop, click here to get $10 credit for free when you sign up: https://www.massdrop.com/?referer=9QRK4Y
Overview
What it is
- Balanced headphone amp with THX AAA technology to produce incredibly low distortion and noise, high power and low heat (AAA = achromatic audio amplifier, meaning ‘colourless audio amplifier’)
- Produced as a collaboration between THX and Massdrop
- Limited edition, but hopefully will be offered again
What it cost
- $350 USD
How it Works
- Utilises an AB amplifier design which is a hybrid of Type-A and Type-B. Type-A is good for producing very low noise & distortion, but creates heat and is power-hungry (i.e. inefficient). B is much more efficient, but produces significantly more distortion
- THX-developed AAA technology addresses Type-B issues to achieve better-than-Type-A performance while staying small and cool
- The video at this link is an interview with the lead engineer for the AAA technology if you’d like to know more: https://twit.tv/shows/home-theater-geeks/episodes/242
Design & Connectivity
Inputs:
- 1 pair of XLR-3 (gold-plated)
- 1 pair of RCA (gold-plated) plus RCA pass-through to allow chained devices (e.g. a second amp / pre-amp)
Outputs:
- 1/4 in (6.35 mm) TRS gold-plated
- 3.5 mm TRS gold-plated
- XLR-4 balanced gold-plated
Other Features
- Auto-off – can be switched off, but there is no benefit in keeping this amp warm. Switches the amp off after no signal for a period of time
Specifications
I’ve rarely seen an amp with such thorough, published measurements. It’s very impressive how transparent Massdrop / THX are being with their published specs and it’s no wonder given how strong the performance figures are.
All parameters measured at 0 dB gain, 1 kHz, with balanced inputs and 300-ohm load unless otherwise noted. Even more specs available via the Massdrop product page.
- Frequency response: + 0.01 dB / – 0.01 dB 20 Hz–20 kHz; + 0.05 dB / – 0.10 dB 10 Hz–80 kHz
- Input impedance: 50 kOhms balanced or unbalanced
- Power supply: 24 VDC inline brick
- Dimensions: 8.3 x 9.1 x 2.2 in (210 x 230 x 57 mm)
- Weight: 3.4 lbs (1,520 g)
Balanced Output
- Output power: 6000 mW, 16 ohms, <1% THD (watts per channel)
- Output power: 6000 mW, 32 ohms, <1% THD (watts per channel)
- Output power: 800 mW, 300 ohms, <1% THD (watts per channel)
- Output power: 400 mW, 600 ohms, <1% THD (watts per channel)
- THD: -123 dB, 32 ohms, 100 mW: 0.000071%
- THD: -118 dB, 16 ohms, 100 mW: 0.000126%
- IMD: -123 dB, SMPTE 70 Hz + 70 kHz, 300 ohms: 0.000071%
- IMD: -124 dB, DFD 18 kHz + 19 kHz, 300 ohms: 0.000063%
- Crosstalk: -127 dB, 300 ohms: 0.000045%
- Noise (A-wt): 2.4 uV, potentiometer at nil
- Signal-to-Noise Ratio: 136 dB, 300 ohms, <1% THD
- Gain: 2x , 8x, 16x (+6, +18, +24 dB), selectable via front switch
- Output impedance: < 0.1 ohms
Single-Ended Output
- Output power: 3000 mW, 16 ohms, <1% THD (watts per channel)
- Output power: 1700 mW, 32 ohms, <1% THD (watts per channel)
- Output power: 200 mW, 300 ohms, <1% THD (watts per channel)
- Output power: 100 mW, 600 ohms, <1% THD (watts per channel)
- THD: -140 dB, 300 ohms, 100 mW: 0.000010%
- THD: -128dB, 32 ohms, 100 mW: 0.000040%
- THD: -123 dB, 16 ohms, 100 mW: 0.000071%
- IMD: -117 dB, SMPTE 70 Hz + 70 kHz, 300 ohms: 0.000141%
- IMD: -125 dB, DFD 18 kHz + 19 kHz, 300 ohms: 0.000056%
- Crosstalk: -90 dB, 300 ohms: 0.003162%
- Noise (A-wt): 1.2 uV, potentiometer at nil
- Signal-to-Noise Ratio: 136 dB, 300 ohms, <1% THD
- Gain: 1x , 4x, 8x (+0, +12, +18 dB), selectable via front switch
- Output impedance: < 0.05 ohms
Balanced vs Unbalanced Use
- The amp produces less power when using single-ended
- Difficult to accurately compare inputs due to different cables and voltage outputs, but Overall, sound quality is audibly equivalent once volume-matched to account for greater power output from balanced inputs/outputs
Sound Quality
- Offers a true wire-with-gain sound – incredibly transparent, particularly at the pricepoint
- Outstanding separation of instruments and sounds and a well-layered soundstage
- No enhancement of soundstage size (or decrease) – allows the recording and the headphones to speak for themselves
Check out the video for comparisons with the Burson Audio Fun and the Bottlehead Mainline amplifiers.
