Reviewer's References & Disclaimers

About the Reviewer’s Reference Thread

The purpose of this thread is to provide a common location to allow reviewers to post information they want to reference (i.e. link to, rather than including inline) across multiple reviews. This will help keep individual reviews more concise, while still allowing the inclusion, by reference, of appropriately detailed information on repetitive subjects.

Common occurrences of this include:

  • Equipment Used (pictures are encouraged)
  • Music Auditioning Playlists
  • Measurement Rig Setup/Conditions
  • Reviewer Preferences/Biases
  • Disclaimers
  • Technology/Feature Descriptions common to Multiple Products (e.g. MQA, ADEL, DSD etc.)

Use of this thread is optional and provided for convenience/consistency.

If you do decide to use this thread, then please observe the following:

Equipment Used Entries

These should include links to the equipment being referenced and, where possible, a picture of the unit in your system (pictures can be added/amended over time and do not have to accompany an initial entry). Links may tie back to the original manufacturer’s site or or Amazon (using “The HEADPHONE Community” affiliate link, as detailed in the reviewer guidelines).

If the equipment used varies with later reviews, which is typical as systems change and evolve, you should make a new post and reference that instead of editing earlier posts - this preserves the details of the original references as used in the referencing review.

Adding more detail, adding pictures, or editing such a referenced post, without changing the actual equipment list, can be done at any time and in the original post.

Referencing Other People’s Entries

In some cases, it might be desirable to reference an existing technical description of some technology shared between an item you are reviewing that someone else has already detailed. For example, for MQA or ADEL or DSD or some other technology.

I think this should be encouraged. As such, if you see such a post from me in this thread, on a topic you want to reference in your own review, feel free to link to it (do NOT copy and paste its content into your text). For other people’s content, you should ask first.

Multiple Reference Posts for Existing Subjects

It is perfectly fine if you want to write up your own description of a technology (etc.) and reference that in your reviews or posts. This means there may be multiple descriptions of a given technology or subject.

This is expected.

But this is NOT the thread for opinion pieces (see below).

Technical Material (including Erroneous Descriptions & Opinions)

If you do make a post here describing a technology or feature, please ensure sure it is both technically accurate and factual and does not become an “opinion piece”.

Opinion is welcome, but belongs in the main body of the review itself or in a general discussion thread on the topic at hand!

We reserve the write to edit, remove, or redirect references to inaccurate or inappropriate entries here.

Discussions and Non-Reviewers

There is no issue with general discussion around posts made in this thread. It will be common for members to want to ask questions about gear used in auditions, listening lists, or on technology issues. However, broader, ongoing, discussions about specific technologies should be carried into the appropriate primary threads.

Please keep this thread free of memes and reaction posts. Pictures should be limited to gear references and/or supporting technical illustrations. Keep things on topic and with as high a signal-to-noise ratio as possible. Posts going against these requests for this thread will likely be deleted without warning, rather than moved.

For example, if you want to talk about your opinion on, say, MQA then that belongs in one of the primary MQA threads. Posts on this thread should be limited to accurate descriptions of the technology.

NOTE: If this thread is abused, then it will get locked down so that only reviewers can post in it.


Torq’s Review Equipment & Material

In order to be as consistent as possible when reviewing headphones, DACs and amplifiers, I try to stick to a specific subset of my audio gear collection across all reviews. Some reviews need special accommodation, particularly if I am reviewing several pieces as a “system”, but in general my reviews utilize my highest-performing gear so as to get the best out of whatever item is being listened to.

I will typically also use the best performing connections, which means if balanced connections are available then those are used. For components with both balanced and single-ended connections, I will generally listen for audible changes between them and note those in the review.


My primary sources used when reviewing gear are:


I use two primary amplifiers for headphone listening/review, with a bias towards solid-state:

I also, occasionally, use the iFi Audio Pro iCAN Headphone Amplifier & Pre-Amp.

The SPL Phonitor X, which I’ve reviewed here, provides a neutral, transparent, reference which is most useful when assessing the character of a DAC or headphone. Tone and transparency of headphones is always assessed using this amplifier.

When used in reviews, the WA234 MkII MONO is run with RCA 13EM7 signal-tubes, Takatsuki 274B rectifiers and Takatsuki 300B power-tubes. Where this amplifier is pictured, I often put Sophia Electric Princess 274B (Punched Plate) and Princess 300B (Punched Plate) tubes in as they have a more pronounced glow and heater pattern , are much prettier to look at and the tube glow shows up much more readily.


For on-the-go listening, and reviews centered around that activity, I have a couple of options, and tend to use these more when reviewing IEMs, though will also match them with full-size headphones when I want to see how well they’re driven by a DAP.

These DAPs span the realm from very-small and light to something I don’t necessarily want to carry in a pocket How/when they get used depends on what I’m doing. My “every day carry” DAP is the SR15, with the SP1000m and NW-WM1Z being employed for more critical listening and for longer-duration trips (or when I’m not space/weight constrained).


Most of my headphone reviews will have specific entries where I make comparisons to what I feel are the most appropriate/similar cans, drawn from my current collection:

And the following Massdrop “x” models:


I tend to only use IEMs when I cannot use full-size headphones, so I have a much smaller reference set here:

The Zeus XR in “R” mode are what I use as a neutral IEM reference point currently.


Headphones are always reviewed using the manufacturer-supplied cables; however, this may not always be reflected in my pictures as I use my own, modular, cable system for post-review listening and photography often occurs at this point rather than during the review-listening phase.

Interconnects are AudioQuest Wind (XLR) and AudioQuest Columbia (XLR and RCA) cables (“Columbia” is a discontinued line; closest current product is the “Water” line). USB Cables are AudioQuest Diamond, or my own proprietary design, TOSLINK cables are glass (rather than the more common plastic) from Lifatec.


The majority of the music I use in my evaluations is in “Red Book” CD format (16 bit, 44.1 kHz), most of which comes from CD rips; an initial playlist for my audition listening can be found here. Where appropriate/referenced I utilize a number of high-quality, high-resolution, albums, needle-drops, and also some native DSD content.


Torq’s Standard/Basic Review/Audition Music/Playlist

I have a standard playlist I like to use when testing pretty much any piece of audio gear, and it’s a bit long so you can expand it to see it.

Playlist/Track List
  • A Case of You - Diana Krall (Live in Paris)
  • Almost Blue - Diana Krall (The Girl in the Other Room)
  • Alone Together - Chet Baker (Chet)
  • Along This Road: Kono Michi (Yv) - Ottmar Liebert (One Guitar)
  • Appalachia Waltz (version for Solo Cello) - Yo-Yo Ma (Solo)
  • Baby I’m A Fool - Melody Gardot (My One And Only Thrill)
  • Beautiful Love - Shirley Horn (You Won’t Forget Me)
  • Better Together - Jack Johnson (In Between Dreams)
  • Brasilia - Robert Len (Fragile)
  • Bruch: Scottish Fantasy, Op.46 “Adagio cantabile” - David Oistrakh & LSO - Decca Sound: The Analogue Years 1954-1968
  • California - Joni Mitchell (Blue)
  • Chameleon - Trentemøller (The Poker Flat B-Sides, Chapter Three)
  • Cold, Cold Heart - Norah Jones (Come Away With Me)
  • Control - Overwerk (Conquer)
  • Crystalline - Björk (Biophilia)
  • Don’t Give Up on Me - Solomon Burke (Don’t Give UP On Me)
  • Don’t Lose Your Steam - Gregory Porter (Take Me To The Alley)
  • Ellis Island - Mary Black (Looking Back)
  • Every Morning - Keb’ Mo’ (Keb’ Mo’)
  • Gift from the North Country - Bob Dylan (The Freewheeling’ Bob Dylan)
  • Hazey - Glass Animals (ZABA)
  • Hey Joe - Jimi Hendrix (Experience Hendrix)
  • Inaudible Melodies - Jack Johnson (Brushfire Fairytales)
  • Into the Mystic - Marc Cohn (Listening Booth: 1970)
  • Isn’t She Lovely - Livingston Taylor (Ink)
  • Jealous - Labrinth (Jealous)
  • Just a Little Lovin’ - Shelby Lynne (Just A Little Lovin’)
  • La Grange - ZZ Top (Tres Hombres)
  • Learning How to Love You - John Hiatt (Bring the Family)
  • Leather - Tori Amos (Little Earthquakes)
  • Love on Top - Beyoncé (4)
  • Maybe Not Tonight - Glen Hansard (Rhythm and Repose)
  • Mining for Gold - Cowboy Junkies (The Trinity Session)
  • Night and Day - Joe Pass (Virtuoso)
  • Nobody Knows the Trouble I’ve Seen - Sam Cooke (Night Beat)
  • Novocaine - Amber Rubarth (Sessions from the 17th Ward)
  • One True Thing (Acoustic) - Jewel (Sweet and Wild)
  • Partition - Beyoncé (Partition)
  • Perfect Sense Pt. 1 - Roger Waters (Amused to Death)
  • Red or Dead - Randi Tytingvåg (Red)
  • Rise - Overwerk (Conquer)
  • Samson - Regina Spektor (Begin to Hope)
  • School - Supertramp (Crime of the Century)
  • Semi-Charmed Life - Third Eye Blind (Third Eye Blind)
  • Shining Moon - Cowboy Junkies (Whites Off Earth Now)
  • Show Me the Place - Leonard Cohen (Old Ideas)
  • Sing Sang Sung - Gordon Goodwin’s Big Phat Band (Swingin’ for the Fences)
  • Son of a Preacher Man - Dusty Springfield (Dusty in Memphis)
  • Sonnentanz - Klangkarussel/Will Heard (Sonnentanz)
  • Spectrum (Say My Name) [Calvin Harris remix] - Florence+ the Machine (Spectrum - Say My Name)
  • St. Louis Gal - Cécile McLorin Salvant (Woman Child)
  • Sweet Baby James - James Taylor (Sweet Baby James)
  • Sweet Disposition - The Temper Trap (Conditions)
  • Talkin’ Bout a Revolution - Tracy Chapman (Tracy Chapman)
  • The End - The Doors (The Doors)
  • The Rat - Infected Mushroom (Army of Mushrooms)
  • The Trawlerman’s Song - Mark Knopfler (One Take Radio Sessions)
  • The Very Thought of You - Nat King Cole (The Very Thought of You)
  • There Is No Greater Love - Ron Carter/George Coleman/Jimy Cobb/Mike Stern (4 Generations of Miles)
  • There’s More to Life Than This (Live at the Milk Bar Toilets) - Björk (Debut)
  • Titled - Christine and the Queens (Tilted)
  • True Love Ways - Buddy Holly (Buddy Holly Lives)
  • Twist In My Sobriety - Tanita Tikaram (Ancient Heart)
  • Video Games - Lana Del Rey (Born to Die)
  • Walk On The Wild Side - Lou Reed (Transfomer)
  • Wasting My Young Years - London Grammar (If You Wait)
  • When I Fall In Love - Nat King Cole (Love is the Thing)
  • White Foxes - Susanne Sundfør (White Foxes)
  • Wild Horses - Tim Ries (The Rolling Stones Project)
  • Wish You Were Here - Pink Floyd (Wish You Were Here)
  • Woodstock - Joni Mitchell (Ladies of the Canyon)
  • Words of Wonder - Keith Richards (Main Offender)
  • World Without End - A.A. Bondy (American Hearts)
  • You Turned to Me - Elvis Costello (North)
  • You Want It Darker - Leonard Cohen (You Want It Darker)

And then if I get through all of that there are some albums that I like to listen to as entire albums:


  • Carmen (Jessye Norman) [Bizet]
  • Cowboy Junkies – The Trinity Session
  • Jean-Michel Jarre - Zoolook
  • Julia Fordham – Julia Fordham
  • Mike Oldfield – Tubular Bells
  • Paul Simon - Graceland (1986 original release)
  • Saint-Saëns ‎– Best of Saint-Saëns [Saint-Saëns]
  • Symphonies 5 & 6 (Karajan/BPO) [Beethoven]
  • Tanita Tikaram – Ancient Heart
  • Tori Amos – Little Earthquakes
  • Tracy Chapman – Tracy Chapman

Torq’s Headphone Measurement Rig & Practices

Headphone measurements that I post in threads here and in reviews on are performed using a miniDSP EARS measurement rig. The headphones under test are driven from an RME ADI-2 DAC fs using the macOS version of “Room EQ Wizard” (REW).

Measurements are taken using a calibration of 84 dB @ 300 Hz (sometimes at 1 kHz also) - this level should be taken into consideration in the context of Equal Loudness Contours - as our perception of frequency response changes with volume level and the differences are significant enough to change the apparent tonality of a headphone with changes in listening level.

Note: Measurements performed on different rigs are not directly comparable, though comparisons to other miniDSP EARS’ derived measurements should be close enough to be useful.


In order to minimize external influences this is mounted on a custom isolation base and within a custom isolation cell. The isolation cell is designed to minimize/eliminate any reflections from the backs of the headphones being tested back to the microphones as well as to attenuate/eliminate external noise factors.

Positioning & Clamping

The positioning of a headphone on the measurement rig can significantly affect the results, so to help alleviate this, posted measurements are the average of five different placements of the headphone on the stand.

For each placement, measurements are performed both free-standing - i.e. with only the natural tension/clamp/geometry of the ear-cups to the rig and gently clamped (via low-tension elastic bands to avoid unnecessarily compressing pads and changing the normal volume of the ear-cup).

Compensations & Curves

In the past I only simply posted the microphone-calibrated, but otherwise uncompensated (no headphone-curve) Frequency Response curves. These are done using the “RAW” calibration profile supplied by miniDSP.

Going forward I will also post Frequency plots using both the miniDSP-supplied “HEQ” (headphone) compensation profile and a custom compensation profile of my own. The custom profile is intended to show something that’s closer to what I actually hear while listening than I find with the supplied “HEQ” compensation.


Torq’s Isolation Measurements

Rather than try and guess what level of isolation a given pair of closed-back headphones yields, and how well that matches to the needs of a given individual, situation or environment, I have started using a simple, repeatable, process to measure the isolation provided in a more applicable manner.

There are two types of isolation to consider:

  1. Leakage: How much sound escapes from the headphones and is audible to an outside listener.
  2. Attenuation: How much outside noises are attenuated for the wearer of the headphones.

Leakage Measurements

These are presented as the listening volume level, for a given set of frequencies, necessary for an outside listener to discern any sound coming from the headphone.

The listening levels are measured using a miniDSP EARS unit, while the headphones are fed a single-tone sine-wave at the respective frequencies (100 Hz, 300 Hz, 1 kHz, 3 kHz, 6 kHz and 10 kHz - lower frequencies are less audible to humans, and peak sensitivity is typically around 3 kHz).

Audibility is determined by averaging the lowest level at which several listeners first detect any sound coming from the headphone at a distance of 1 meter, in a 40 dB environment (equivalent to a quiet room) for each frequency individually.

The resultant values are graphed. A value of, for example, 85 dB @ 3 kHz means that a 3 kHz tone (roughly the center point for the human voice) could be heard by an outside listener, one meter away form the headphones, in a 40 dB room.

Higher values are better.

Attenuation Measurements

Most hearing-protection devices have a Noise Reduction Rating (NRR), measured in decibels; however this value does not directly reflect the actual reduction in sound level at the ear! This means that the best available in-ear hearing protectors, which have a NRR of 33 dB, would not, in fact, reduce a 100 dB concert to 67 dB.

Instead, the accepted methodology de-rates the quoted NRR protection value by 7 dB (to account for variances in fit/application), and then you divide that result by 2. This means that those NRR 33 dB protectors, in a 100 dB environment, only actually reduce the SPL to 87 dB:

(NRR 33 dB - 7 = 26 dB) / 2 = 13 dB reduction : 100 dB - 13 dB = 87 dB.

Don’t ask me … I didn’t come up with this stuff!

That’s for in-ear isolation. Over-ear (muff) is less effective and consequently the best available over-ear SPL reduction carries an NRR of 30 dB. Such an ear-muff is very thick and deep, and at odds with the design of most audiophile headphones. This is important as it sets an upper limit for what any headphone can potentially do - and since most are not designed to provide protection they will have much lower ratings.

Put another way, headphones are much better at keeping sound in than out, and expecting any closed-back, non-active-noise-cancelling headphone, to provide significant attenuation of outside sounds is likely to prove disappointing. In an outdoor or public environment, such as riding the bus, you’re still going to be able to hear conversation, traffic noise, etc. in any quieter patch of music, in track-breaks, and so on … especially if you listen at lower levels.

Even the best, professional, fully-rated, over-ear hearing protection will not shut environmental noise out entirely!

Note: I am currently working on a measurement methodology that provides a consistent way to assess this NRR in accordance with industry standards, and will begin adding this measurement to reviews as soon as I am happy with the results.