[bluishgreen]

Quote:

Would it make sense that to me the amplifier would make no difference considering I the C421 is my first amplifier?  + I just realized how softly I listen to my music as I often am teetering on the edge of imbalance with my low impedance headphones.

Or rather, it's your first external amplifier...you can always compare it to the built-in amplifiers of whatever devices/computers you currently use...  
 
The external amp is more about sound quality than sound quantity/volume, although it serves both purposes with higher-impedance phones.  However, it also isn't a silver bullet if you are unhappy with the quality of your current phones' sound (especially if they are already more than loud enough) or if your source output that you plug it into is noisy/low-quality.  Except for bass boost features, ideally the amp shouldn't be changing the sound at all, other than amplifying it, so it's only going to improve things if your built-in amp is the weak link and degrading things.  And even then, if you plug the external amp into that same built-in amp/output (because maybe it's your only available output) then it's just going to forward-on a louder version of what you didn't like to begin with, unless you have a line-out port or use an external DAC to bypass the built-in amp/output/soundcard.
 
In any case, if you are referring to the opamp and whether it matters which one you buy--I've only listened to the AD8620, but the general consensus seems to be from the main two choices:  the AD8620 has a neutral-to-slightly brighter sound signature, while the OPA2227 has a neutral-to-slightly warmer sound signature.  There may be other subtleties, but that's probably the most prominent aspect you'd notice, and a decent rule-of-thumb to go by.  There's also a third choice, although JDSLabs seems to recommend the AD8066 specifically for higher-impedance phones, which doesn't really apply to you.  So, I think I'd just go by what basic sound you are looking for in general--do you usually prefer a slightly brighter sound or a slightly warmer sound--and go with that.  Keep in mind that we're talking about subtleties here, since again, the amp should generally be neutral and shouldn't be radically changing your sound, other than cleaning-up the non-neutrality that another amp left behind...
 

 

[Cassadian]

Great post.  Thanks for the information,  I guess it makes sense that the line out from my iPod into the JDS Labs C421 shouldn't make too much of a difference if the AD8620 is neutral/bright as stated.
 
Quote:

Or rather, it's your first external amplifier...you can always compare it to the built-in amplifiers of whatever devices/computers you currently use...  
 
The external amp is more about sound quality than sound quantity/volume, although it serves both purposes with higher-impedance phones.  However, it also isn't a silver bullet if you are unhappy with the quality of your current phones' sound (especially if they are already more than loud enough) or if your source output that you plug it into is noisy/low-quality.  Except for bass boost features, ideally the amp shouldn't be changing the sound at all, other than amplifying it, so it's only going to improve things if your built-in amp is the weak link and degrading things.  And even then, if you plug the external amp into that same built-in amp/output (because maybe it's your only available output) then it's just going to forward-on a louder version of what you didn't like to begin with, unless you have a line-out port or use an external DAC to bypass the built-in amp/output/soundcard.
 
In any case, if you are referring to the opamp and whether it matters which one you buy--I've only listened to the AD8620, but the general consensus seems to be from the main two choices:  the AD8620 has a neutral-to-slightly brighter sound signature, while the OPA2227 has a neutral-to-slightly warmer sound signature.  There may be other subtleties, but that's probably the most prominent aspect you'd notice, and a decent rule-of-thumb to go by.  There's also a third choice, although JDSLabs seems to recommend the AD8066 specifically for higher-impedance phones, which doesn't really apply to you.  So, I think I'd just go by what basic sound you are looking for in general--do you usually prefer a slightly brighter sound or a slightly warmer sound--and go with that.  Keep in mind that we're talking about subtleties here, since again, the amp should generally be neutral and shouldn't be radically changing your sound, other than cleaning-up the non-neutrality that another amp left behind...
 

 

 

[bluishgreen]

Quote:

Great post.  Thanks for the information,  I guess it makes sense that the line out from my iPod into the JDS Labs C421 shouldn't make too much of a difference if the AD8620 is neutral/bright as stated.
 


 

 
The C421 with a line-out (LOD) made a noticeable improvement with my iPhone 4S--both in quality and volume--although that was while using larger phones that I'd never actually use outside the home.  I haven't tried it with my usual "outside world" phones, which are nothing special--Sennheiser PMX 680i, which I love for the price and the purpose I bought them for, but are by no means audiophile or anything.
 
Also, just to clarify--when I was talking about "subtleties", I was referring to the subtle difference between the two main opamp choices of the C421.  I didn't mean to imply that you would only get a subtle improvement if you bought an amp compared to your existing setup (ie, I wasn't trying to dissuade you from getting one).  Although I was trying to explain that nothing is guaranteed.  You may get a big, noticeable improvement, and you may get little-to-no improvement--it's hard to say unless someone has the same equipment as you.
 

 

[Cassadian]

Ah, I already have one.  It's just I haven't noticed any gigantic differences, but the fact is that I haven't really been using FLAC, nor my over ear headphones.

 

[SteveSatch]

I currently use a Fiio E11 with iPod and Fiio L9 LOD and Brainwavz HM5 headphones.  Anyone think I would gain anything over the Fiio E11 in this setup if I got a C421?

 

[bluishgreen]

Quote:

Ah, I already have one.  It's just I haven't noticed any gigantic differences, but the fact is that I haven't really been using FLAC, nor my over ear headphones.

 
OK--I misunderstood and thought you were still determining whether to buy...
 
Of course, even if it doesn't do what you hoped with your current headphones, a great amp like this will serve you well if you plan to buy other headphones--especially higher-impedance ones that need an external amp to drive them.
 

 

[Cassadian]

Could it run the Denon AH-D7000?
 
Quote:

 
OK--I misunderstood and thought you were still determining whether to buy...
 
Of course, even if it doesn't do what you hoped with your current headphones, a great amp like this will serve you well if you plan to buy other headphones--especially higher-impedance ones that need an external amp to drive them.
 

 

 

[bluishgreen]

Quote:

Could it run the Denon AH-D7000?
 


 

That'd be more a question for someone who has those headphones--I've never really tried them to know how they'd sound.  In terms of power, the C421 seems to have enough power to drive most phones, and it is transparent enough that it should sound good with most phones (it shouldn't "get in the way" of a good set of phones) but whether the two sound good together is always a subjective thing.  Although it can help when a person does have both and somewhat objectively describes them for others.
 

 

[gelocks]

Quote:

Could it run the Denon AH-D7000?
 


 

It should.
I run my D5000s easily!
 

 

[JRoMan]

So I had the chance to borrow an OPA2227 c421 for almost 2 weeks. I have had the AD8620 opamp version for over 2 months and it gets daily weekday use. The other amp was brand new, so I tried to put about 20-30 hours on it before comparing directly, which I did over about 3 separate sessions in the past few days.
 
In the end I thought the difference between the two were not easily perceptible to my ears even though I had preconceptions about how I thought it was going to sound. This was tested mostly with HD25-1 II and iPhone 4S as source. Tracks ranged from 256kbps AAC to 320 kbps mp3 and 16-bit Apple Lossless.
 
YMMV

 

[Mutnat]

My C421-2227 finally arrived yesterday!  It actually shipped March 1st, so it must have been stuck in Canadian Customs for a while.  For anyone from Canada thinking of ordering, the stated value on the customs form was $174 (the price at the time I ordered--I think it's gone up a few dollars since then?) and I was assessed HST (12% so just under $21) plus the standard $8.50 handling fee Canada Post always charges if you get dinged at customs.
 
I've had it playing (shuffling my iPod) for about 13 hours now to start the burn-in process.  I've listened to a few tracks during the process and so far I'm pretty impressed.  Using my HD25-I-II's.  I'll check back in later with more impressions, and try to compare it a bit to my D-Zero and just the iPod's output w/o an amp sometime over the next week or two.
 
EDIT: I also meant to say that I was surprised just how small the C421 is...  it looks bigger in pictures.  I'll take a comparison photo with the D-zero and iPod at some point.

 

[Mutnat]

Quote:

In the end I thought the difference between the two were not easily perceptible to my ears even though I had preconceptions about how I thought it was going to sound. This was tested mostly with HD25-1 II and iPhone 4S as source. Tracks ranged from 256kbps AAC to 320 kbps mp3 and 16-bit Apple Lossless.

Interesting!  Thanks for posting that.  I kept putting off ordering for days trying to figure out which op-amp to order.  It sounds like with similar equipment (same cans and a 4th gen iPod Touch) that there may not be a night and day difference, so that makes me feel a bit better about my choice. 

 

[JRoMan]

Quote:

Quote:


Interesting!  Thanks for posting that.  I kept putting off ordering for days trying to figure out which op-amp to order.  It sounds like with similar equipment (same cans and a 4th gen iPod Touch) that there may not be a night and day difference, so that makes me feel a bit better about my choice. 

Yup. I feel better now, too!

 

 

[SteveSatch]

What rechargable battery does it use and where is a good buy to buy a spare or two?

 

[ClieOS]

I have received a loan unit of OPA2227 based C421 this morning to compare to my AD8620 version as well. I haven't put enough time on the new comer but suffice to say, I can already tell the subtle difference between the two C421. It is almost like the last time I compared the stock cmoyBB (which is OPA2227 based) to the AD8620 rolled cmoyBB, except this times both C421 sound much better than both the cmoyBB in every way. Like last times, the AD8620 wins over OPA2227 for me again. Not something night and day, but enough to call out a winner.
 
However, this is not to say AD8620 crashes OPA2227 in every way. I love the AD8620, but I can understand why someone would find it V-shaped sounding and prefer the OPA2227 instead. It has more to do with the slight difference in presentation between the two opamps (and I had observed the same in cmoyBB as well) - AD8620 has really great soundstage and portrays the image in a very 3D fashion. In a way, it is almost better in imaging (especially in depth) than the O2 and that's quite an amazing feat on its own. OPA2227 on the other hand puts everything upfront with a sense of rich and warmness between the tones. If we were to take O2 as our reference for what 'totally neutral' / standard should be, then AD8620 would be the equivalence of what 3D TV meant to normal TV (where you get the surreal 3D effect) while OPA2227 would be equivalence of sitting close to a HD TV vs. at normal distance (where you get to see the fine detail in individual element but not quite so over the whole picture).
 
As mainly an IEM user where soundstage is generally more limited, the extra layer of depth that AD8620 brings to the table is a real killer feature to me. It just goes really well with all kind of IEM (*the synergy with Etymotic ER4S is unbelievably good for an IEM that is always considered to be flat sounding). But that same extra layer of depth might not be that appreciated for full sized headphone user (where soundstage is already good) or simply for those who rather prefer an upfront presentation. Instead, I would think they will find AD8620 adds a sense of hollowness to the presentation which might not be to their liking. That's probably why AD8620 is interpreted as V-shaping by some, even though the FR curve is perfectly flat for both opamps.
 
So what is my early conclusion? I'll still recommend C421 with AD8620 over OPA2227 for its more rounded presentation. But for those who rather like a little bit more richness over imaging, the OPA2227 based C421 could work out better for them. Both are really great sounding amps, and I think the choice is every bit personal preference as it is performance.
 
Will write a more completed review once I have enough time with them, and will include a comparison to JDS's own O2 as well as cmoyBB (plus a few others).