I disagree. Grados are singularly well-damped. (See some of purrin's graphs and reports on Grado decay.) Connecting them to the current-FOTM super-low-output-impedance amplifers causes them to over-damp, resulting in the harshness and tizziness that many people cite for their dislike of Grados. The reason Grados do well with many tube amps is not necessarily the "warmth of tubes," but that the output impedance is quite a bit higher than your run-of-the-mill low-output-impedance SS amp. Grados do quite well on 15 ohm output impedance and higher.
This gets complicated to a certain extent because the low impedance of Grados causes fall-off with OTL amps as lowering the bass cut-off point results in extremely large and super-expensive output capacitors (which means shortcuts/cheaper alternatives are often used). Hybrids experience this fault, too, because many of their output buffers still require blocking caps and unless sized large enough, cause bass roll-off or phase distortion in low frequency response.
Bottom line, for the best sound with Grados - finding the right amplification is not necessarily so simple.
I would entirely disagree with you on the basis that electrical damping is essentially a fantasy (go ahead and tell me I'm wrong, and then go ahead and tell JBL, McIntosh, BK Butler, Rod Elliot, QSC, Accuphase, and so on that they're all wrong too). Damping is primarily (like 99%) a mechanical feature, and Grados rely on nothing but the driver itself (more or less) for this (and their drivers are good; I'll give you that); if you actually reviewed the CSDs you're blindly referencing (and you can actually go beyond purrin's measurements, and go look at CSDs from He&Bi and GE too), most of them (being Grado models) exhibit ringing in the upper treble (and FR and IR will also show this) - and believe it or not, some people just don't like bright cans that have resonance artefacts. And that ringing isn't really hard to predict based on the enclosure design. If you want to look at a "singularly well damped" example of a headphone, the Koss Pro4/A and 4/AA are good candidates. Most 'stats will also put up a very clean CSD too (because the drivers are extremely well controlled). They sound very different from Grados. And no, I'm not saying ringing is a bad thing by any means here (even purrin makes the comment that the RS-1 "look worse than they sound" on measurements). It's part of their coloration and their flair - and it doesn't suit everyone.
Their impedance is very stable, so changes in Zout won't result in any significant FR changes unless you increase Zout substantially (which will act on the bass region where the impedance peak is; here's a great article on the topic: http://en.goldenears.net/index.php?mid=KB_Columns&document_srl=1389) - what's really quite disturbing about your argument is in one hand you're taking the modern marketing line of DF as pushed by makers like Crown and Anthem (who are both miserable shills with a history of saying or doing anything just to close a sale), but you're then using that fallacy to argue against itself (and saying that DF is "bad'). Sure, high Zout *can* be a good thing depending on overall system Q (which is an unknown here), but we'd be talking about LF response based on the impedance of the Grado drivers (it would be most pronounced with the GSK and PSK). Basically you'd be talking about a slight bump to the LF as Zout went up; I can tell you from experience that going between 2 and 500R doesn't do much of anything, even with the GSK. As far as what happens if you over-damp (which you're not gonna do without physical modification) - it should not ever produce a "harsh" or "tizzy" sound (because that would be a result of ringing, which critical damping will prevent...) - it'll just be over-damped. And at that point they'll just sound dead and lifeless. So in summary, *IF* DF were worth phoning home about, it would actually REDUCE the harsh/tizzy sound (by better controlling the driver's movement), and decreasing it would decrease damping (which would increase ringing and tizziness (like I said, your argument is logically troubling)) - now of course in the real world that doesn't hold up, because DF isn't worth phoning home about, and all you'll get as you run Zout up is a slight bass boost (which I could see people interpreting as a slight warmth, but we're talking very slight). If you wanted to make them ring worse, you could EQ up the treble or get really nasty and setup a filter to target and excite the points at which the enclosures already want to ring (you'd have to measure them before you could build this) and they'd sound absolutely disgusting at the end of it (why anyone would want to do this to any headphone or speaker I have no idea, but it is theoretically possible). Now, if all you're getting at is "more bass compensates for their brightness" (either because it's changing phase response, or by masking, or a combination of both) - that's fine. But we have tone controls for a reason.
They're sensitive, stable, and low impedance - they don't want for much in terms of power, and you can get the same party from more or less anything that'll give up the power they do want in a clean way. Clean and quiet is king, only because I think a lot of people will have an issue listening to hiss or pot rustling inherent on a lot of the shoddier amplifiers out there. But as gradofan pointed out - good current supply, clean tracking, and you're pretty much set. If you prefer the coloration of tubes or equalization, or whatever else - that's a personal choice, and should be left up to the end-user to explore. I think I need to qualify that my statements are being taken massively out of context though (is it because they're hurting someone's bottom line I wonder?) - my comments were specifically directed at preproman's question, and based on the knowledge that he has a (very dapper looking) pair of D7000s that I'm assuming he has suitable amplification for. Whatever is driving those will have no issue driving any Grado. If someone wants to experiment with various tubed or non-tubed products on their own, that's their choice - and I provided a list of the four manufacturers I see most commonly suggested when people for ask a good amplifier for their Grados (which usually come from a more subjective "amps are all different" crowd and do include a combination of tubed and untubed devices) - as a starting off point. Of course there are many different amplifiers out there, and people will find enjoyment in a variety of products that may not be considered "right" by the mainstream - and that's also perfectly fine (but I still think having a starting point is helpful versus "go forth and frolic"
). But I'm going to take an issue when you try to force everyone's experiences into some "grand theory of the Universe" to either explain your own experiences, or sell product.
Can anybody give me some input on how a Bellari HA540 will match with the Grado SR325is? Thank you.
Someone (I forget who now...) was posting about their HA540 like two days ago - just dig back a few pages. I think he said it worked out pretty well.
