Your answer is pretty much six posts back. Nothing images as well as an HD800...tonal balance is another matter though. And the Stax headphones (SR007/009) are both open back TOTL "summit-fi" electrostats. Almost all reviews and comparisons that you're going to find for those phones will be out of drastically better DACs and specialized amps - making any comparison questionable because of significant equipment-level testing differences. Not a lot of people are going to listen to a 7520 out of a Headamp Blue Hawaii.
The real competitors against the 7520 are those in its similar ergonomic/use or price bracket: closed back, low impedance mid-fi phones, Fostex T50rp mods and HiFiMan orthos, and pre-"summit fi" open orthos and dynamics priced between $150-700. In that bracket, you have a lot of stiff competition: the Focal Spirit Pro/Classic, NAD Viso HP50, PBS M4U1 & 2, UE6000, LFF's Paradox, Dan's Mad Dogs/Alpha Dogs, HE-4/5, HE-400/500, and the venerable Sennheiser HD600/650 to name a few. Bixby, who from my experience has good ears and certainly plenty of experience, made a good list of phones in this bracket that he thinks the 7520 beats out in resolution. That's not an insignificant list: the HD600/650 series is pretty detailed when ran through a good DAC/Amp match - they scale up really well.
Thanks for your reply. That's a good list and I appreciate bixby's response, thank you very much, but wanted others' input if you don't mind. As you can probably tell I'm not after 'pretty detailed', but 'as detailed as possible'. You mention HD800 imaging well - imaging is part of it but not really what I'm talking about when I say detail/resolution.. Nor is tonal balance which I have clearly explained a couple of times. You also mention the highest end Stax which of course I know almost nothing else will compare to (I was talking more about the entry level Stax systems that might be comparable to a $400 headphone). Just for information I've heard amongst others: Senn 650 (nice presentation, nowhere near detailed enough for me), HD800 (one time unbalanced which sounded thin, the other balanced out of a big amp which sounded brilliant), AKG K701 (owned these for 6 years, over 400hrs burn in, used with custom EQ correction, amazing detail even compared to HD800), Beyer DT250 80 (owned for 20 years or more), T70p (reference, extended bass, amazing clarity, detail, and 'liveness' but even harsher than 701 in the highs unEQed), Stax SR2170, 407, 507 (in Dynamic Audio, Tokyo, best detail and realism I've heard so far), LCD3 (nice, a little boring I thought), Momentum, etc, and lots of others. I have read the Focal Pros are very detailed and can see this in the 30Hz and 300Hz square wave graphs, so appreciate the comment that the 7520s are more resolving than this, but havent heard them, and others like the NAD, 650, and some planar magnetics are supposed to be laid back and not necessarily that detailed.
I guess the main thing I'm trying to do is work out if these really are very resolving and can compete with the best (and will be an improvement in my system) or as you say it's more like people with not much experience of good headphones or lower end systems are getting these as their first real pair and doing the reviews. I have read a couple of good reviews, one that said they were only bettered by JH13 iems, another who had HD800 and vaguely said they conpare, but nothing solid. Even one account of "Sony 7520 versus HD800 detail" would be enough for me to see where it fits.
By the way my system is Surface Pro/Mac Pro with Kingrex UD384 (ESS Sabre) DAC / UPower, Scherzo Audio Andante amp with custom made USB cable (split data/power), hand made silver/teflon interconnects, Isone Pro, ie very highly resolving, realistic, and even in the ballpark of some of the highest-end systems I've heard.
I do restoration mastering work and have plenty of years experience in the professional audio/audiophile worlds.
Cheers
