** REVIEW: M-Stage Headphone Amplifier (using AKG K702) ** - Page 2

Good question on the M-Stage.  It definitely lacks treble.  I find myself wanting to add it, but my Nano's EQ settings introduce major distortion - a major flaw in Apple's Nano products.  I would like to add in an affordable, quality EQ to correct that.  The O2 for example is crystal clear, allowing the K702 to breathe and shine with its natural brightness that I like.  I'd hoped the M-Stage would just tame that brightness a little, but in fact it darkens it too much as to obscure some detail compared to the more precise and transparent O2.  The O2 is a very transparent amp, just as the designer seemed to want.  It is pure volume for the source, nothing more, it seems to me.

As for tonality and timbre, it's hard to say, because the simple lack of treble on the M-Stage may be the only factor obscuring clarity and detail, which would be solved if treble was returned.  The O2, in comparison, is crystal clear and sounds and effects can be heard on it that are not nearly as distinguishable, or at all distinguishable, on the M-Stage.  In addition, and this is a big one, the sustain on the O2 is much better.  Because of the darkened sound quality on the M-Stage, the sustain on effects and chords die quicker.

The problem with the O2, to me, at least with the K702 is that it indeed is stripped of tonal colors I guess one could say.  What I mean, is I compare it to my old Grace 901, (although of course it is nowhere near in remotely the same category).  The Grace had a way of making music sound non-musical.  It was as if I had laid the song on an operating table, and separated it with a scalpel into all its component parts, and then spaced them out apart from each other.  It was an ideal sound engineering piece - after all, it was designed for that - but it was not enjoyable to listen to music with it.

The O2 in any case, is similar to the Grace to my ears in that it seems to strip the color and warmth from the music.  The M-Stage may be dark and not as detailed, sadly, but when you're listening to it you find yourself really enjoying the music as a whole piece.  It is warm, full sounding, "musical."  These are the same words I use to describe tube amps for example.  The O2, to me, instead strips a lot of that warmth and life out of the song.  So it sounds perfect, but lifeless.  Again, I would call it a poor guy's engineering amp.  Or, the best amp around for the price for those that prefer that sound, or have headphones that would do well with that kind of detail and "coldness."

(When I get my ER-4 back from Etymotic's repair service, if I still have the O2 I am jumping with anticipation to do a test with it, as I think those are headphones that would still sound great with the O2's sound quality style.  The ER-4 sounds extremely great with my little BSG amp, and I think the O2 will be like a deluxe BSG, a portable SS amp of tremendous quality and clarity.  Those Etys will rock, I'm sure).

I hope that this makes some sense.

The Nano's EQ settings are preformed, you can't adjust them.  There is a bass reducer, but it sucks ALL the bass out of the sound, and so sounds like garbage.

The best setting on the Nano is the "Electronic" setting, and indeed it breathes a ton of new life into songs with the M-Stage (or any amp, or no amp at all).  The problem is, as with all of Apple's EQ settings on the Nano at least, is that you immediately begin to hear distortion.  And not just with bass, but with basically everything.

A shame, as those EQ settings really improve the sound of the Nano, adding soundstage and treble, the treble being a big help with the M-Stage.

Yup, AC power is fine, and there are 2 rechargeable 9V batteries installed in the unit which stay fully charged when you listen with AC power.  On battery alone, I've heard you get about 7 hours of play time.

Well Sonitus, I have to disagree about the K702 actually.  I have compared it against lots of heavy hitters on several different amps, and consistently got wonderful sound out of it.  The Glow Audio Amp One was a pristine, crystal clear amp, that moved a K701 I had to new heights of beauty and grace.  Never has music sounded so truly wonderful.  It was the best amp, and the best combo, I've heard yet.  I think the O2 is just a perfect little amp of highest quality, whose SQ I don't particularly enjoy and probably wouldn't with any cans.  We'll see though, if I get my ER-4 back from the shop before I've sold the O2, and am able to do some listening with those two together.

The person I got the O2 from, who built, said unequivocally that the O2 would be damaged by running it without either or both of the two batteries.  True, or why, I don't know but I've been following his advice, even though for my own piece of mind I'd prefer to simply remove the batteries as I don't like mixing batteries with AC power.  I've had batteries pop and catch fire with that experience.  But since these are rechargeable, I don't know.  If anyone knows, for sure, that'd be great.  But as I'm selling the O2 (hint... hint...) I'm not too worried, I did a listen last night to make sure but otherwise it sits here waiting to be shipped.

Thanks for the articles.  I've never liked the SS sound, ever.  The M-Stage is actually an anomaly.  Funny that it is, because it sounds like tubes.  There you go.

Oh, cool!  And since this case is a bit larger than the original slim silver case, there is even more room.  The inside of this gold case is designed like an audio equipment rack.  There are slots to slide in circuit boards, one on top of the other.  So, for example, the current amp circuit board takes up one "shelf" of the rack, and there are more available for other things, like this DAC.  Do you know where it is available?  That would be a really cool thing to add to this amp (for the new buyer that is, I need to sell it - trying to pay down my credit card from buying both it and the M-Stage at the same time).

Thanks again, that's a really cool idea.  I like that the amp is fully moddable.  I spent a night listening to it recently and am just blown away honestly by how crystal clear and transparent it is with the details of each song.  It really is as the designer said it is, like it provides volume for each single aspect of the recording, in full.  Leaves nothing out.  I just guess I personally don't like the solid state sound.  But this amp is about as perfect as one I've ever heard.  If anything, the M-Stage most definitely adds its own flavor of coloration to the sound it reproduces, because it is nothing whatsoever like the O2.  I just like the M-Stage sound "better," though I envy and will miss the perfect clarity and detail retrieval of the O2 for sure.  I've never heard anything else like it except, in a much grander way, the Grace 901.

Charles is on a hush-hush mission for the United States Government, and when I asked him what he's up to on my sat phone, he said if he told me, he'd have to kill me.  So, that's all I have for you Chris.  And I wouldn't ask him if I were you.  He's a bad shot but he has an itchy trigger finger.  You just never know with these monkey secret agents.

BTW, I sent him with my Etymotics and my iPod, and I'm hoping for once they come back undamaged... without blood on them.