[Clutz]

In an ideal world I would be able to easily switch back and forth between both headphones and headphone amps merely by flipping a switch, and while it woudln't be too terribly difficult to construct a device that would let me do that I haven't done that in this case because I'm lazy, but more to the point - I don't have two power supplies to power both amps simutaneously (I'm working on it - but I just don't have the funds right now to build a STEPS - buying the K701 has cleared me out, and I know I'm going to owe on my income tax). Consequently, this review was done by manually switching between headphone and headphone amps.

Currently my HD580s have over 300 hours of play time, and my K701s have maybe 30 to 35 hours on them - so in totally different ballparks. That said, let's start off with a discussion of which combination of headphone and headphone amplifier I prefer over the others.

My PPAv2 amplifier is using the 627/637 opamp combination, approximately 3000uF of rail capacitance from Cerafines, I've set the buffer current to 25mA and the opamps are biased into class-A operation with 1.5mA of current. My Millet-Hybrid amp is using Cerafine caps for all the electrolytics, except for two which I used Nichicon UPW series. All of the film capacitors are Wima film caps, and I'm using the 12FK6 tubes, and OPA551 op-amp as my current buffer (having some problems with my diamond buffer).

Before I go any further, I'm also going to point out that these comments are just my opinions - and are my general impressions.

I definitely prefer the combination of the HD580 + PPA over the HD580 + Millet Hybrid. The 580 + Millet does sound good - particularly with classic rock (CCR) and some metal, but I don't generally find this combination dynamic enough. Two of my favourite artists are Radiohead and The Cure, and I found that the HD580 and the Millet just doesn't reproduce the dynamics and layering of their music nearly as well as the PPA does. I find this particularly noticable with the track "Out of this World" by The Cure and remixed by Paul Oakenfold. Listening to this track using the HD580s and the PPA is an emersive experience, where I feel surrounded by the various layers of the music - but with the Millet the layering is largely lost.

Because I generally strongly prefer my PPA over my Millet Hybrid because I really enjoyed the detail this combination produced, I expected to prefer the combination of the K701 and PPA over the K701 and the Millet Hybrid, but I don't. While my K701s only have about 35 hours of burn in (in my experience burn in is a real phenomenon, but I will not debate this issue here) and so I accept that they are probably currently brighter than they will settle down at - I find the combination of the K701 and my PPA to be overly bright and overly detailed. I definitely find I have to turn the volume down with this combination or I get a headache. With the PPA and the HD580, I keep the bass boost turned all the way down - and I had begun to regret ever installing it - but with the PPA and the k701s, I'm finding I've got the bass boost turned up about 35% of the maximum boost possible in my configuration.

I'm finding it hard to say which pair of headphones I currently prefer. The K701s definitely sound 'quicker' than the HD580s to me and they definitely have less emphasized mid-bass - but the HD580s don't sound sluggish or congested to me. I'll have to wait until I get closer to 300 hours before I reserve judgement. if I had to make a decision today to decide whether I'd keep the HD580s or the K701s, I think I would probably keep the HD580s, as much because they're a known quantity to me. I've listened to them and I know I really like them, where as with the K701s - I'm enjoying them, but I just have less confidence in them because I've had less exposure to them so far. This is definitely making me wonder though if I would prefer the HD600s or HD650s over the K701s.

Anyway

 

[PeeeMeS]

I heard the same thing out of my K701 -> PPA setup
However, I enjoy the brightness and detailed sound, I just wish it had more bass.


Sadly, my PPA doesn't have Variable Bass(it was equipped with gain switch instead)
I would have much prefered Variable Bass, but I bought it used so I can't complain. Maybe in the future I'll have my PPA "upgraded"

 

[Andrea]

Thanks for the interesting read, Clutz.


My guess is, now you'd want to hear the HD650 with your PPA

 

[Clutz]

Quote:

Originally Posted by Andrea Thanks for the interesting read, Clutz. My guess is, now you'd want to hear the HD650 with your PPA

Yes, yes I think I do.

 

[Mercuttio]

Quote:

Originally Posted by Clutz Yes, yes I think I do.

I absolutely adore the 650 out of a PPA. The DT880 I had before simply did not match it at all.

 

[[AK]Zip]

Quote:

Originally Posted by Clutz Yes, yes I think I do.

Thats what I did. I had the HD580's and built a pretty much maxed out PPA. I then ended up with the HD650's and I liked it more. In the end I ended up with a pair of L3000's and found something off with the PPA / L3000 combo. Ended up building a maxed out Millett Hybrid amp and once it was burned in I did come critical listing between the 2 and the PPA was out the door.

-Alex-

 

[Andrea]

Quote:

Originally Posted by [AK]Zip Thats what I did. I had the HD580's and built a pretty much maxed out PPA. I then ended up with the HD650's and I liked it more. In the end I ended up with a pair of L3000's and found something off with the PPA / L3000 combo. Ended up building a maxed out Millett Hybrid amp and once it was burned in I did come critical listing between the 2 and the PPA was out the door. -Alex-

Funny you should say that, since lately I've been just about to get myself a Millett Hybrid but fortunately stumbled on AMB's benchmarks, showing the Millet's high total harmonic distortion (between 0.3% and 0.8% depending on the tubes, the result of high third harmonic distortion as well as second harmonic); so I happily settled with a solid state Intersil buffered amp (which sounds very good btw).

 

[Lavalamp]

Quote:

Originally Posted by Andrea Funny you should say that, since lately I've been just about to get myself a Millett Hybrid but fortunately stumbled on AMB's benchmarks, showing the Millet's high total harmonic distortion (between 0.3% and 0.8% depending on the tubes, the result of high third harmonic distortion as well as second harmonic); so I happily settled with a solid state Intersil buffered amp (which sounds very good btw).

Fear not harmonic distortion!

This is precisely why I'm in the process of building a Millet Hybrid.

Different strokes I guess.

 

[Andrea]

Quote:

Originally Posted by Lavalamp Fear not harmonic distortion! This is precisely why I'm in the process of building a Millet Hybrid. Different strokes I guess.

Yup, "different strokes" is it. If you're totally happy, like I am, with an op-amp and (intersil) buffers amp, which has very low total harminic distortion to boot, why look at tubes & their peculiar distortion characteristics at all?

 

[Clutz]

Quote:

Originally Posted by Andrea Yup, "different strokes" is it. If you're totally happy, like I am, with an op-amp and (intersil) buffers amp, which has very low total harminic distortion to boot, why look at tubes & their peculiar distortion characteristics at all?

Well, that makes the assumption that sound quality increases monotonically with decreasing harmonic distortion. Which may be true, but isn't necessarily true. Music is art afterall, not science. Imagine if we took some of the paintings by the master painters, maybe the Melting Clock by Salvador Dali, and replaced them with hyper-accurate image equivalents - would they be more visually pleasing than they currently are? For that matter, ever heard a pure tone reproduced without it's natural harmonics? If you listen to them for very long they sound creepy, and not terribly musical. I like my PPA and my Millet, just for different reasons.

 

[Solude]

Quote:

Originally Posted by Clutz For that matter, ever heard a pure tone reproduced without it's natural harmonics?

Problem with that is the recording already has those harmonics. Microphones aren't picky on what they pick up. If the instrument created harmonics and overtones... the mic grabs them and they are present on the recording. The amp doesn't need to add its own.

 

[Clutz]

Quote:

Originally Posted by Solude Problem with that is the recording already has those harmonics. Microphones aren't picky on what they pick up. If the instrument created harmonics and overtones... the mic grabs them and they are present on the recording. The amp doesn't need to add its own.

I know, but that's not the point I was making. The point I'm making is that it's not necessarily true that less harmonics is universally going to sound better. Just because on paper something measures better doesn't necessarily mean my ears will find it more appealing. I tend to prefer my PPA over my Millet, but I can accept that other people might prefer an optimally implemented PPA (whatever that means) over a similarly optimally implemented Millet Hybrid.

 

[Clutz]

Iève just put my Diamond Buffers into the K701, and I have to say I think the combination is fantastic. It's gained a lot of the quickness and snappiness of the PPA without the harshness. That said, my headphones have been burned in for another 24 hours since I posted my last review, so that may have a lot to do with it too. I shall have to do a listening test with my HD580s to see what I think.

Anyway, this has got me excited to do a STEPS PSU upgrade for my Millet now- that's supposed to be a much bigger upgrade than this diamond buffer.