Super, but why multiple same headphones ?
As for your question on whether Inhave heard both , I have only briefly heard the SR009 with the Blue Hawaii but that was at a show and I found it thin sounding. But this was in a noisy area I am sure the headphone is capable of a lot better performance.
I don't own multiple units of the same model, but I could understand the reasons. Sometimes it's because of an allegedly difference in production (lots of talk on 007mk1 about it...see HiFiman HE6 too, with 4/6 screws), sometimes it's because of spare parts as they are completely out of production (Sony MDR-R10, Stax Omega). But I may only be for the sake of collecting.
I like to say we're all completely crazy as we cross the "HD600 + Objective2" frontier, which represents a kind of pricetag ceiling for ordinary people. So I won't blame our fellow hobbyists to be crazy, even if they have a different way from mine to be so
BHSE really opens up 009, with lots more of details / air / soundstage than any Stax amp, giving some lushness to the mids (t00bs !) and real impact / volume to the bass. As they have the 1-2 khz Stax coquetry, this amount of air / details may absolutely be perceived as brightness, but it depends on tubes and source. Throw a DS / Sabre-y DAC and keep stock tubes (Mullards re-issue and Shuguang treasures to a lesser extent), you'll have something delicate but undoubtely bright and a bit thin. Take a R2R or warm DAC + other tubes (PSVane, NOS Mullards, Mesa Boogie), it's another story.
It also depends on your reference point and which frequencies you're sensitive too. From my point of view :
- HD800 have a 6 khz peak with tons of details, 100-150 hz hump, something bloomy in the mids (Senn's veil ? )...they're bright, but it's not the same kind of brightness as 009. I like them for ambient, live venues, and everyday listening (games and movies too)
- Utopia are very impactful but not that dynamic, with something fake to my ears : struggling bass (small driver ? See Frog and Ox from La Fontaine), weird FR, robotic sound (think vocoder), and any tape hiss thrown at your face, covering lots of music
- Beyerdynamics all have a "peak of death" between 7 and 9 khz, unbearable to my ears as it has e-dyn grain.
- Fostex TH-900 are boomy phones, but they have some peak around 10 khz, and for me, that's a sound of tinnitus
- Orthos do also have a peak / wall most of the time in the highs, but depends. Abyss is an exemple of this peak, very screechy to my ears.
- 007 have also a kind of peak around 8 khz, but with e-stat mellowness. This dzingy sound, like an ever ringing cymbal, gives a one-note touch to the highs and is one of the reasons I sold mine (lack of impact / bit floating bass and too-veiled-to-be-true tone are others)
- Orpheus clones have the best FR I've ever heard, with nothing of the bit hifi / fake tone of 009 (though impactful and highly enjoyable to me) and throwing 007 dull-sound-which-pretends-to-be-true-but-is-in-its-own-way-faker-than-009 to the dust
All the above are 100% subjective, my journey in this hobby taught me I'm very sensitive to oddities above 6-7 khz (modded HD800 are fine to me), so assume I'm a complete moron if you hear differently, it'll be easier than the everlasting 007 vs 009 fight
Back to the thread, 009 are said to be gorgeous out the DHT 845 amp of
@FrankCooter, but
@jude is the only guy who owns one...and they're a jealous crowd (within which I stand) around this
Ali