(Added Focal Clear MG Professional, Nectar Audio Hive, Razer Opus)
Tier 1 - Almost like the headphones aren't there
Stax SR-009 (Has increased imaging and separation over the SR-007. Dynamics seem slightly better. Unmodded has "Stax fart" similar to modded SR-007A and I assume the original MK1.)
Tier 2 - Near perfect
Nectar Audio Hive (Similar to Stax SR-009 except is more forward sounding and not quite as "ethereal". Slightly more bass impact. Requires at least 400 V RMS energizer.)
Stax SR-007MK2 with Blu-Tack mod (like the SR-007A but with less "Stax fart" for some reason.)
Stax SR-007A with Blu-Tack mod ("Stax fart" a little annoying.)
Stax SR-L700MK2 (VERY similar to Focal Clear. Has slightly more mid-bass impact, midrange is not quite as thick. Instruments seem slightly more separated. Soundstage slightly wider. Very similar to SR-007. Soundstage is a little wider on the SR-007 and it has more lower bass until you do the Blu-Tack mod which evens it out.)
Tier 3 - Excellent
Focal Clear MG Professional (Pretty similar to the non-MG version. Excellent extension.)
Focal Clear Professional (Not the widest soundstage but excellent tonality, dynamics, and extension. Treble could use a little boost.)
Sennheiser HD800S (Super transparent with more bass than Stax SR Lambda Pro. Lightweight but ear pads are large but don't conform well. Great soundstage.)
ZMF Eikon (Similar to the MDR-Z1R but with more even frequency response but less bass extension.)
Tier 4 - Excellent with minor imperfections, beginning of summit-fi
Focal Utopia (Slightly wider soundstage than the Clear. Sounds very similar. A little too thick sounding for me resulting in a "wall of sound" and less instrument separation.)
Sony MDR-Z1R (Closed headphones with great transparency and better bass than HD800S. Amazing for a closed back. Similar to ZMF Eikon but with slight peaks in freq. response that sound a little unnatural at times and better bass extension.)
Sennheiser HD820 (Comes close to the HD800S but isn't as tonally even and soundstage is slightly smaller. Has better comfort, isolation, and bass volume though.)
Sony IER-M9 (A little uncomfortable. Sounds nearly perfect if you can get the fit right. Has more lower-midbass than Z1R which increases impact.)
Sony IER-Z1R (A little uncomfortable. Sounds nearly perfect if you can get the fit right. Could use a little more bass impact.)
Tier 5 - Great with slight annoyances
Campfire Andromeda (Rivals HD800S / MDR-Z1R in transparency and very even sounding. Good everything, except bass is a bit light. Sound stage is a little smaller than with over ear headphones.)
Audeze LCD-4 (Best bass, good but not great transparency, very heavy, prone to driver failures with pressure changes. Mine had a driver failure.)
Tier 6 - Very good but not quite impressive
SendyAudio Aiva (Great build quality, looks good, good frequency response except bass extension is lacking.)
Audeze Mobius (Some of the best bass I've heard but soundstage is small.)
Audeze LCD-2 closed back (Heavy, bass extension and impact are lacking, isolation is poor for a closed back.)
Stax SR Lambda Pro (Super transparent.)
AKG K7XX (Great value. Elastic may go bad over time.)
Sennheiser HD600 (Slightly more realistic frequency response than HD650.)
Sennheiser HD650
Razer Opus (Very good timbre and frequency response. Treble and bass are could use more clarity.)
Tier 7 - Good, beginning of hi-fi
qdc Neptune (Good value, sounds like the Andromeda, but a little more muffled and more bass and bass extension).
Beyerdynamic DT880 (Annoying treble peak, ~8.5 kHz.)
AKG K702 (Painful headband.)
Beyerdynamic DT990
Grado SR-80e with L cushions (L cusions improve sound quite a bit, kind of uncomfortable, tons of midbass, good transparency.)
Tier 8 - Pretty good
Denon D2000
Shure SE846 (Terrible value. Sounds similar to the IE80.)
Sennheiser IE80 (Good value, but sound a little muffled compared to higher end stuff.)
Etymotic ER4XR (Good as earplugs. Sound not very impressive.)
Sennheiser HD598 (A little muffled sounding.)
Bose Triport (Good 3D sound positioning. Lightweight. A bit muffled overall.)
Koss Porta Pro (Very light weight. Sound is good for price. Open back design.)
Tier 9 - Slightly better than average
Westone W30 (All mid-range. Not very good for listening to music.)
Grado SR-60i (Poor fit, comfort and bass. Decent transparency. Would probably sound better with L cushions.)
KZ ZS6 (Treble is peaky.)
VJJB-V1S (Sound is very good for price.)
ViSang R02 (Sound is very good for price.)
Tier 10 - Average, but not bad
Panasonic RPHJE120S
Panasonic RP HT355