I've reviewed most of the posts on the HE-500's and still don't have a good idea of what SS / Hybrid amps (for <$700) match them well. 
 
My Millett Hybrid MiniMax matches them pretty well (maybe very well)... but... I'm wondering if any might match better - such as the Lyr, or EF5, or Audio-gd, or something else, like the Virtue Two.2. 
 
From the results with my WA6 SEm, I'm guessing tube amps may not match them too well - it's got lots of power, but seems to need more current output, and lower output impedance to match them really well.  They clip with it... and... I don't think its tube selection.  I'm a bit surprised, since it drives everything else really well - Grados, Denons, Senns, ATH's, etc.
 
Maybe the Millett MiniMax is as good as it gets - which is pretty good... even my Shellbrook Maxi Moy is pretty good with them.
 
 

Actually... the more I listen to this set up... the more I think it may be the best I've heard - and I've heard some pretty good ones.
 
I'm using the Marantz SA8001 as the transport, the Monarchy M24 tube DAC, the Monarchy M24 tube Line Stage and the Millett Tube Hybrid MiniMax as the amp to drive the the HE500's.
 
The more the HE-500s burn in with this set up the better they sound, even with the stock cable.  A bit like a combo of the "new version" HD580/600/650's, with the RS-1's and AD2000's all rolled into one, with a lot of the detail, clarity and resolution of the Stax SR-507/007's.  Just a rich, warm, textured, organic sound throughout all frequencies with no over-emphasis anywhere.  Great bass, mids and highs... great PRAT and slam... and... not too dark, or too bright.  Though, I could see some might think they're a bit bright, or that their upper mids might be a bit "glassy."  But... in general... everything just seems right.
 
About the only thing I might critique at the moment is the ambience may be a wee bit too great - sort of sense of too much space / air... maybe... not sure yet.  I guess some might call this "soundstage." 
 
But... overall... pretty impressive in all respects.
 
UPDATE:  Actually the more I listen to them and swap between the HE-500's, AD2000's and HD580/600/650's (new version) - they more all these sound very similar.  I'm not sure why, but they do.  I'm not sure whether it's because they're all very "transparent" phones, and are reflecting the sound quality of the source and amp, or whether the source and amp are imposing their sound on all the phones... or... whether they all just sound very similar.  It doesn't matter, because they all sound superb.  But... it does cause me to wonder, whether it makes sense to keep all of these phones, if they all sound so similar.               

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gradofan2 said:

Actually... the more I listen to this set up... the more I think it may be the best I've heard - and I've heard some pretty good ones.
 
I'm using the Marantz SA8001 as the transport, the Monarchy M24 tube DAC, the Monarchy M24 tube Line Stage and the Millett Tube Hybrid MiniMax as the amp to drive the the HE500's.
 
The more the HE-500s burn in with this set up the better they sound, even with the stock cable.  A bit like a combo of the "new version" HD580/600/650's, with the RS-1's and AD2000's all rolled into one, with a lot of the detail, clarity and resolution of the Stax SR-507/007's.  Just a rich, warm, textured, organic sound throughout all frequencies with no over-emphasis anywhere.  Great bass, mids and highs... great PRAT and slam... and... not too dark, or too bright.  Though, I could see some might think they're a bit bright, or that their upper mids might be a bit "glassy."  But... in general... everything just seems right.
 
About the only thing I might critique at the moment is the ambience may be a wee bit too great - sort of sense of too much space / air... maybe... not sure yet.  I guess some might call this "soundstage." 
 
But... overall... pretty impressive in all respects.           

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That's the "bloom" in decay that K3cT and I described. It gives it its liquid mids but also is an addition to the recording. You also get slightly uncontrolled bass as a byproduct. Overall though, the cans are excellent and worth the price IMO.

Gradofan,

Could you be hearing the best things of each of those headphones in the 500s? I liked the openness of the 701s, the fun of the RS-1, the speed and details of a stat. The new orthos do this in one headphone and bumps up the bar set by those references.

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shahrose said:

I just got my HE-500...with a broken right earpad. It has a pretty large gap between the pad and frame. I'll post pics later.
 

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While we're waiting for the "new and improved ear pads," is there another way for the pads to be fastened securely to the housing / frame?  Can you use double sided tape to fasten them?  I would think that would work about as well as anything. 
 
I hope the "new and improved ear pads" are much easier to remove and replace.  If I had to do that, I would have no idea how to do it without breaking the tabs on the replacement pad. 

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gradofan2 said:

While we're waiting for the "new and improved ear pads," is there another way for the pads to be fastened securely to the housing / frame?  Can you use double sided tape to fasten them?  I would think that would work about as well as anything. 
 
I hope the "new and improved ear pads" are much easier to remove and replace.  If I had to do that, I would have no idea how to do it without breaking the tabs on the replacement pad. 

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To be honest, I haven't found a good way yet. Just be as careful as possible and don't bend the earpads too much because the plastic backing cracks with minimal force.

I have a soldering tool that can bend the last plastic tab under the frame without too much force. I've also used hemostats.

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happy camper said:

I have a soldering tool that can bend the last plastic tab under the frame without too much force. I've also used hemostats.

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That's a great idea, I bet a hair dryer would work as well.

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wuwhere said:

That's a great idea, I bet a hair dryer would work as well.

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I don't believe Happy Camper is using a solder IRON, rather a small hooked tool to catch the tab.   I can't think of a faster way to ruin a pad that with a soldering iron.  Perhaps gently heating the plastic with a low temp hair dryer might make the plastic less brittle, but might also cause the plastic to separate from the pad. 
 

The more I think about the harder it is to post opinions on the HE-500. This due to the stock cable versus the HE-6 balanced cable, I have both and after about 3.5 days I gave up on the stock cable and returned to the HE-6 balanced cable. As stated above by others the HE-500 can indeed be driven by a lot more amps, however I still think it sounds best when driven by the Red Wind Audio Signature 30.2 (30 wpc). So in summary the HE-500 sounds best to me when used with the HE-6 balanced cable and driven by the RWA Signature 30.2

hiflight said:

I don't believe Happy Camper is using a solder IRON, rather a small hooked tool to catch the tab.   I can't think of a faster way to ruin a pad that with a soldering iron.  Perhaps gently heating the plastic with a low temp hair dryer might make the plastic less brittle, but might also cause the plastic to separate from the pad. 
 

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Correct Ron. I'll see if I can link something like it. But I like the idea of heating up the plastic to make it more pliable. The straight fork is what I use. When you put the first tab in, rotate the other two into place. Then use the tool to get under the pad and slip the last tab in place by using the fork to turn it under.

http://www.beautech.com/double.cfm

Just out of curiosity, I tried to remove it. Its actually very easy, to remove without breaking the plastic. But putting it back in is the hard part. After I had the 3 tabs in, I had to bend it slightly by the 4th tab then use a small screwdriver to carefully get the tab under. Very tricky.

Here's an idea that I just tried and it worked. Using a nail clipper I slightly trimmed one of the tabs and it was the last tab that I inserted. It made it easier to insert.

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wuwhere said:

Here's an idea that I just tried and it worked. Using a nail clipper I slightly trimmed one of the tabs and it was the last tab that I inserted. It made it easier to insert.

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That's a good idea actually...

Well... after a few more hours with the HE-500's, with the stock cable, driven as follows:  M24 DAC > M24 Line Stage > Millett MiniMax > Phones - they sound superb... but... I don't find them really much better than my AD2000's, and HD580's (new version, modified).  It's really very hard to tell much difference between them, except for very minor differences - they all sound incredible. 
 
When I drive them as follows:  M24 DAC > Millett MiniMax > Phones, they seem a bit darker than than when the Line Stage is in the loop, and darker than either the AD2000's, or HD580's.  I suppose that's the result of the added gain / boost the LS provides to the HE-500's.  So... I assume... that means they might better distinguish themselves from the others... IF... driven by an amp with greater power (e.g.  the Lyr, EF-5, etc.).  And... perhaps... they also would brighten up with the HE-6 cable. 
 
I hate to have to buy another amp to really hear their potential.  Would the HE-6 cable make that much difference?
 
Update:  When I saw the review on another forum of the HE-500's, which suggested that the HD650's sound just as good with a well matched set up, I was afraid I might not find much difference between the HE-500's and the "new version" HD580/600/650's (mine have the same drivers as the "new version" HD650's).  But... I had to see for myself.
 
And... I'd have to "correct" that other review... it's not how expensive the set up is, which drives the HD580/600/650's, but how well matched it is to the properties of those phones - that determines how great they sound.