[size=large]The Audio-gd Compass vs. the Meier-Audio Corda Opera[/size]
INTRODUCTION
Thinking about this review beforehand, I realised there are a number of similarities between the two of them. The obvious ones are of course that they are both DAC/Amps from experienced designers with USB input and a pre-amp function (this last one not yet present on my test-version). But the two of them also started out on their "head-fi life" receiving a fair number of reviews from a select group of listeners. In the case of the Corda Opera this was because of
Todd's
Opera loaner program. In the case of the Compass, it is of course Kingwa's marvellous joint design effort with the people from head-fi.org. In both cases, the programs have generated a lot of extra publicity here for the respective products.
The comparison will consist of listening impressions from the Compass and the Opera separately first (using them as a combined DAC/Amp), followed by impressions of the DAC-out of the Compass fed into the amplifier section of the Opera.
EQUIPMENT AND SETTINGS
Transport
-Digital coax from Pioneer DV-575A. (I know, I desperately need something better than this.) I chose to use this kind of digital input in preference to both USB and optical, both of which invariably resulted in lower sound quality than coax. I'm just trying to show both units in the best possible light.
Cables
- Audio-gd Canare digital coaxial connecting the Pioneer to both the Compass and the Opera
- Audio-gd Shark analog interconnect (Monster plugs) between the DAC-out of the Compass and the analog-in of the Opera
- All equipment was fed by ordinary power cords, with just some minimal peak filtering upstream.
Audio-gd Compass:
Technical details
See
Peete's review.
Settings for review
Gain=low (13dB); Amp set to Neutral; Earth opamp installed in DAC section.
Burn-in time since the moment of arrival of the Compass: 320 hours (both amp and opamp)
Meier-Audio Corda Opera:
Technical details:
[size=x-small]2 headphone outputs( 0/120 Ohm output impedance ); Maximum output 13V / 500 mA; Gain switch: maximum gain factors -5 / +8 dB; Crossfeed filter switch; 2 pairs of analog inputs, input impedance 12 kOhm; 1 digital S/PDIF input; 1 digital USB-input; 1 pair of volume-controlled preamplifier outputs. Gold-plated input jacks; Silver plated headphone jacks (Neutrik); Silver plated heavy duty switches; Alps Blue potentiometer for volume control; 25 Watts toroidal transformer for the analog section; 7 Watts toroidal transformer for the digital section; 110V and 220V mains power switchable; Power uptake 12 Watts; Built-in groundloop breaker; Schottky rectifying diodes in the power supply; Double regulated voltage lines; Low impedance electrolytic buffer capacitors (Nichicon); Total Buffer capacity 80.000 uF.; Bypass capacitors in the power supply.; Polystyrol and polypropylen capacitors in the signal path; Metalfilm resistors in the signal path; LM6171 opamps biased into class-A using LM334 current sources; 2 BUF634 buffer amplifiers at left and right headphone output channel; (Active) balanced headphone ground; 3 BUF634 buffer amplifiers at the balanced ground headphone output channel; PCM2704 as USB-to-S/PDIF receiver; CS8420 as S/PDIF receiver (in high-jitter-reduction mode); PCM1794 D/A converter-chip; LM6171 opamps biased into class-A for I-V conversion; Sampling frequencies / resolution: 8..96 kHz / 16, 20, 24 bit (S/PDIF);32, 44.1, 48 kHz / 16 bit (USB). Star-grounding; Ultra short signal paths; Signal paths and signal path components at the bottom side of the PCB for maximal shielding. Weight: 3.9 kg. Size: 27.6 x 27.8 x 8,7 cm.[/size]
Settings for review
Gain=low (-5dB); Crossfeed=off.; low z (0 ohm) output
Note the exceptional difference in gain between the two amps (-5dB vs. 13dB)! This does clearly illustrate the necessity for a lower gain setting in the Compass (which will be there). You might wonder if it wouldn't be more fair for comparison to put the Opera in high gain (8dB), which would be closer to the Compass's 13 dB. Curiously, the high gain of the Opera has a huge effect on the sound signature of the amp. The soundstage gets 'flattened' to a very high degree and becomes unpleasantly aggressive and direct. Therefore, I decided to use the gain setting which IMO showed the Opera in the best light. (At least with the AKG K500.)
Both units received at least a couple of hours warm-up before review.
Volume matching was done, rather unprofessionally, by ear, using pink noise.
Headphones
- AKG K500 (stock cabling) ('Phones I know and love very well by now.)
- Grado SR-325i (stock cabling) for some tracks.
COMPARISONS
[For those of you who have less time on their hands or lack the stamina to sit through all of my (slightly repetitive) impressions and comparisons. Just scroll down to the discussion and conclusions.]
[size=x-small]Dmitri Shostakovich
Symphony No. 15 in A major
1. movement-Allegretto
London Philharmonic Orchestra
Bernard Haitink
(Decca)[/size]
As mentioned earlier in this thread, this is my go-to test track. It's a very varied orchestral piece employing every possible sonority and instrument combination you can think of and a variety of percussion. The recording is simply perfect, 1978, representing how brilliant analog recording could be. (Before things took a serious nose-dive in the early 80's in the first years of digital.)
Compass
It's easy to love the way everything is so well-balanced and full-bodied. From the upper high treble detail to the bass focus. Things that strike me as missing however, are a better definition of the woodwind (there is also an impression of sameness to the colour of the instruments)and the soundstage is surprisingly small (although not cramped).
Corda Opera
Everything is really distant compared to the Compass, but this results in a much wider and deeper soundstage. Glockenspiel notes still sing, but on the whole the highs seem muted. Separation is quite good (larger soundstage helps here), but still not as excellent as with the Compass. Excitement really suffers from lack of detail, focus and dynamics. However, the cymbal clashes (rather complex to resolve fully) are handled just as well here as the Compass does. Only they're situated in their proper place at the back of the orchestra now, and not in your ear. Background here seems marginally less quiet.
Compass (DAC) -->Corda Opera
Oooh, that really solves the muddiness. Things are still far more distant than with the Compass alone, with more soundstage. Although the last is a bit reduced compared to the Opera alone, that frustrating lack of detail is gone at least. That said, the upper range is still missing that last bit of definition, and what's even more strikingly absent is that sheer excitement and impact that the dynamics and directness of the Compass brings when used on its own. However, things are probably much more natural this way.
The difference between the Compass and the Opera is somewhat like standing in the middle of the orchestra (Compass) and standing at the back of the hall, perhaps even under an overhanging balcony (Corda Opera). Combining the two puts you right in the middle of the hall.
Antonio Vivaldi
Concerto for two mandolins in C major RV558
1. movement: Allegro molto
Il Giardino Armonico, Milano
Giovanni Antonini
(Teldec)
Il Giardino Armonico must be one of the best things to have happened to HIP (Historically Informed Performance) practice. Particularly when they're playing the music of a compatriot. Going all out, bringing passion and aggression in equal measure and not afraid to push their instruments to the limit. Nice clear and balanced recording, as expected from this label.
Compass
Plenty of excitement, although the amount of detail can become a bit overwhelming when it's presented in such a forward way. All that authentic string sound can develop a tendency to become harsh, although partially at least this is sheer honesty on the part of the Compass. There is some smear in the mandolin sound, the fast notes are not as well defined as they should be and have a tendency to run together. But wow, gotta love those dynamics!
Corda Opera
This is certainly the more relaxing listen. The difference in soundstage is quite noticeable, but far less so than with larger orchestral pieces. Funny, you don't really miss the detail here, although obviously a lot of it is lacking. What is most remarkable here is the sameness in the colour of the instruments, both in the strings and in the woodwind. Everything feels fed through a rather cheap cd player. A definite lack of sparkle. This is also noticeable in the repeated plucked strings of the mandolin, which, however, don't smear here.
Compass (DAC) --> Corda Opera
More direct, slightly less soundstage. Still, unfortunately, too much detail is absent. It just lacks the bite that is needed. The fast mandolin notes are much, much better articulated here, than with the Compass alone though. Instrument colour has significantly improved, but is not up to the level of the Compass alone.
Wolfgang Amadeus Mozart
Symphony No.40 in G minor, KV550
3. movement: Menuetto-Trio
Prague Chamber Orchestra
Charles Mackerras
(Telarc)
Moderately paced music for small orchestra. The recording is a rather problematic one. It's recorded very well, but in a very resonant acoustic which is almost impossible to resolve fully. Yet, in my experience, it's a very good test for the quality of equipment to see how far it gets in resolving it.
Compass
Soundstage is pretty well-defined, although very underrepresented. Strings are nicely detailed, but somewhat "tizzy" (sibilance?), making them a bit uncomfortable. Resolving this acoustic to the degree that it does is no small feat, although instrument separation is still far from ideal. Horns are good, but do develop some slight grain. The harpsichord continuo is nicely separate from the rest of the orchestra, but lacks that last bit of focus. Background is very quiet.
Corda Opera
It certainly manages to paint the big picture convincingly, but detail, focus and especially separation are all far from ideal. Horns sound simply horrible, no brassy sheen to them at all. The harpsichord continuo can be made out, but isn't well separated from the rest of the orchestra.
Compass (DAC)--> Corda Opera
A nice balance again, although the true acoustic of the venue is still a little underrepresented. Horns are remarkably better. The continuo stands nicely separate and is fairly well focussed. However, when it comes to instrument separation the Compass solo still scored the best.
Ludwig van Beethoven
String quartet in F minor, Op. 95
3. movement: Allegro assai vivace, ma serioso
Gewandhaus-Quartett
(NCA)
Rather fast and aggressive string quartet movement, with quick stops and turns. The recording is quite direct, but very detailed.
Compass
Not much of a soundstage, although decay is well reproduced. There's a lot of definition to the strings and separation is just right. However, there is a hint of sameness to the sound, perhaps caused by a that last touch of warmth that's missing from the presentation. Highs are so well-defined as to border on the abrasive, but not yet uncomfortably so.
Corda Opera
Quite a bit more soundstage and an even better reproduction of decay. Strings are more pleasantly rounded, but not so that you might feel that detail is missing. That said, it does have a slight muted or stifled quality to it. Separation is not very good, but okay. There is still a similar sameness to the colour of the strings. Overall a very good result from what's, up till now, proving to be the underachieving DAC.
Compass (DAC) --> Corda Opera
Wow, soundstage and separation both strike you as much better from the get-go. Even the decay has more structure to it, like you can even discern the shape of the hall. There's much more space between the instruments and individual colour of the instruments registers much more clearly.
Still, compared to the Compass solo, a tiny bit of detail might still be missing, although the extra warmth here is a welcome compensation. The well-defined dynamics here also make this the most exciting listen of the three.
César Franck
Pièce Heroïque, in B minor
Jean Guillou
(Dorian)
A short late 19th century piece for organ, quite varied in nature going from ruminative to....well...heroic. Jean Guillou pulls out all the stops here (ok, I just had to say that), probably using a greater variety of different registrations than good taste would allow. (I love it.) The Van den Heuvel organ of St Eustache in Paris is a lovely monster, quite recently build (1989). Certainly, going by the sound alone, it's almost indistinguishable from the late 19th century Cavaillé-Coll organ building tradition.
In my opinion, reproducing the sound of a big 19 century-style organ well is one of the greatest challenges you can give any piece of HiFi equipment. The complexity of sonorities, the intricacies of the higher harmonics, the enormous dynamic and tonal range and the very resonant venues present a truly daunting task.
Compass
You gotta love this degree of definition. Voices are very nicely separate. However, it's only in the quieter passages that you get some sense of the huge acoustic this is recorded in. It feels rather like a small chapel. (And it isn't. Less than two months ago I happened to walk past this church in Paris. It's frickin' huge!) As usual there is a hint of sameness to instrument colour.
Corda Opera
So much detail is missing here and there's a distinct lack of separation as well. The result is relatively "woolly" and diffuse. There is a better sense here of how large the church actually is, but also in this respect the real definition of the acoustics is seriously lacking. The lowest notes (always a challenge, certainly through headphones) are just laughably badly reproduced. Not much more than some vague rumbling. And all that sparkle that the 'brass' registers should bring is hardly present either.
Compass (DAC) --> Corda Opera
Now you're at a larger distance from the organ. It's only this combination that manages to paint a truly 3-dimensional picture. After all, this organ is a huge beast, not all the registers should sound like they emanate from the same point. Voices really float in the air now, something I did not hear previously, and there's quite a bit more colour to them too. Even the lowest notes are 'gripped' rather well. You can clearly make out those first 'huffs' of air being blown through the pipes at the start of each note. So much more dynamics too, and finally you can hear the true size of the venue.
And yet, even here there's still that difficulty in resolving the complex upper harmonics that can really put that thrilling sparkle on the Trumpet registers. Quite an achievement nonetheless.
Richard Strauss
Die Frau ohne Schatten-"Nun wil ich jubeln"
Julia Varady, Hildegard Behrens, Plácido Domingo, José van Dam
Konzertvereinigung Wiener Staatsopernchor
Wiener Philharmoniker
Georg Solti
(Decca)
The finale of the opera. Two sopranos, a tenor and a baritone singing their hearts out with a small choir and a huge orchestra in full swing thrown in for good measure. General neo-Romantic operatic mayhem.
Compass
Decent separation all around, but the whole thing does appear very "compacted", like it takes place in a large living room and not the huge Grosser Saal of the Vienna Konzerthaus. There is a little grain to the voices as well, particularly noticeable with the baritone. Details in the orchestra don't really jump out at you as they should.
Corda Opera
All of a sudden, everything has a place in a much larger soundstage. Interestingly, although the soundstage has widened to a large extent, it is not really any deeper (this is probably simply not resolved). Still, there's at least the sensation of better resolution, simply because things have more "Lebensraum". Unfortunately, there's an overall glare to it that rather appears to obscure detail too.
Compass (DAC)--> Corda Opera
Soundstage is not necessarily wider than with the Opera alone, but depth (a little) and resolution (a lot) have improved. And that annoying "blanket" of glare has completely disappeared. This still remains a horribly complex recording to resolve fully, but the combo is simply miles better than the single units. Separation in the orchestra is much higher, although, compared to the Compass solo, there might be a smidgen less detail. Instrument colour is here far and away the best of the three too.
Claude Debussy
Preludes (Livre I)-La cathédrale engloutie
Krystian Zimerman
(Deutsche Grammophon)
This piece for solo piano describes the legend of Ys, where a cathedral that lies sunken off the Breton coast of France. On clear mornings it rises up from the water and the music of the organ and the ghostly Gregorian chant of the monks can be heard. It explores the full dynamic and tonal range of the piano.
Compass
The notes have weight and definition, but lack a little sparkle. The decay sounds way too thick/dense to be entirely natural. There's a fairly decent amount of "growl" to the lower notes. Again, the slight lack of warmth is also noticeable, just as that sameness in instrumental colouring. And lower notes do seem to lack that last bit of grip and definition.
Corda Opera
The opening notes seem to 'float' far less than they do with the Compass. Acoustic cues are all there, but seem 'glued' to the sound of the piano. The upper range of the piano lacks all true sparkle, almost (but not quite) as if the lid of the piano is closed. Lower sonorities are simply vague and there appears to be less 'blackness' to the background as well.
Compass (DAC) --> Corda Opera
Now there's a much better sense of the acoustics and there's simply a lot more of it too. It stands far more separate from the sound of the piano, although it's still not quite ideal. Both separation and definition in the sound of the piano itself have hugely increased. In retrospect, I only now notice how notes do not have that tendency to "run together", like they had with both the units on their own. There's a lovely weight to the notes now, you can really clearly hear the sound of the hammers hitting the strings. And yet, some of the sparkle that should be here is absent or muted (the Compass alone, though still not ideal, does this better).
Francis Poulenc
Figure humaine-"Liberté"
Netherlands Chamber Choir
Eric Ericson
(Globe)
A medium-paced piece for chamber choir. The text is a poem by Paul Eluard, an ode to liberty, poignantly set to music by Poulenc in occupied France (1943). The piece, set for two 6-part choirs, is rather taxing on the choir as a whole and particularly on the sopranos whose vocal line keeps rising towards the end, culminating in a solo high E (above high C).
Compass
Certainly not as direct a presentation as you might expect from previous impressions. There is a lack of individual colour to the singers. They are fairly well separated, but not to the extent that it becomes easy to pinpoint the individuals. The acoustics are not that well separated from the choir. The sound of the sopranos, however taxed, does never become harsh.
Corda Opera
Choir is very distant. Separation is rather comparable to that of the Compass, but, as usual, detail over the whole range (mainly mids and highs) is lost. The choir here is noticeably less "clustered", although it is still not possible to pinpoint the individuals with any ease. There is an uncomfortable glare in the sopranos, especially towards the end. The final high E just fails to send that shiver down your spine like it should (and does with the Compass).
Compass (DAC) --> Corda Opera
It's amazing what this does for ease of listening. Everything takes place in a much larger acoustic, but also against a really black background. Finally, here you can easily pinpoint the individual singers, but it is most of all the absence of all that glare that makes this a much more enjoyable experience. Individual dynamics of the singers com through amazingly well. And that high E really hits the spot.
Interlude
In the following selections I will be using both the AKG K500 and the Grado SR-325i. However, the most important impressions will always come from the K500, because they make any limitations in the reproduction much more apparent than the Grado's do. The Grado's are simply too forgiving of both source and amplification. The AKG's were obviously designed with the recording studio in mind, the Grado's just for enjoying music. But I included them so some of you who might be interested can get an impression of how they work with the Compass.
Frank Zappa
You Are What You Is
Track 4: Goblin Girl
(Rykodisc-Latest (1998) remaster)
I don't think I've heard 'amplified music' (I'll keep using this term throughout, it will come in handy later) ever better recorded than by Frank. The guy was truly a universal genius in all aspects of music. The album "You Are What You Is" is simply a miracle of overdubbing done well. There's no end to the details you can discover here. And the song Goblin Girl is no exception.
Compass
Focus, punch, definition and separation, it's all there. Drums come through very nicely separate from everything else, situated at the back. It's just the bass that could be focussed a little better (but the K500 could be partially to blame here).
Corda Opera
This takes you quite a few steps back in distance to the music. Some of panning effects do have some more soundstage here to develop and sound more 3-dimensional. But overall the sound is very muted, much less detailed, much less engaging.
Compass (DAC) --> Corda Opera
Well, that appears to get rid of most of the muddiness. And the resolution of the complexity is now really benefiting from the larger soundstage. Still, this doesn't really compensate for the loss of detail when compared to the Compass solo. The whole thing feels underplayed and a little dull.
Grado impressions
Little to say here. Details gets a big boost, but you have to hand in almost all of the 3-dimensionality. They obviously sound most detailed and engaging from the Compass.
Genesis
A Trick of the Tail
Track 7: A Trick of the Tail
(Virgin-2007 remaster)
SACD-layer
Just some rather slickly produced prog-rock in quite a decent remastering. I'm using the SACD-layer here, so this comes straight from the analog outs of my Pioneer player. (Thank goodness that it's miles better at playing SACD's than it performs with ordinary redbook.) So, this just tests the difference between the amps.
Compass (amp)
There's not a whole lot of soundstage here, but a whole lot of detail and bite to every instrument and even the vocal lines. All the transients are really expertly handled.
Corda Opera (amp)
The canvas gains enormously in width and depth. Everything is very nicely separate, but there's a frustrating lack of detail, particularly in the high treble.
Grado impressions
Nothing surprising here. The 325i's just add their typical Gradoishness and basically show the AKG's just how it should be done with this music almost all areas (that is, apart from the soundstage, of course). The same differences between the two amps as noted with the AKG's can also be heard with the Grado's, but are a lot smaller due to the forgiving nature of the Grado's.
Wintersun
Wintersun
Track 2: Winter madness
(Nuclear Blast)
Now what kind of label do we put on this? For now "progressive Viking metal" will have to do. Fast, hardhitting, melodic and very intricate and multilayered. Pair this with a slightly less than perfect recording and any setup will have hard job deciphering it all.
Compass
An amazing number of details manage to come through. All those fast guitar riffs, synth-lines (hey, there's even a harp in there, rather hard to make out). However, it's hard to escape the creeping feeling that the K500's have serious problems keeping up with all of this.
Corda Opera
Funny, this is probably the first time that a noticeable change in soundstage does not occur when switching to the Opera. The harp comes through a little better now, but unfortunately detail on the whole really suffers and the bass becomes rather unfocussed and thumpy. Yup, dullness is here again. (Something that really shouldn't be happening with this music.) Even Jari's amazing shredding is not very involving.
Compass (DAC) --> Corda Opera
Surprisingly, this is almost worse. Everything has cleared up quite a bit (although the harp has slightly less focus), but the serious lack of detail remains. And it feels so much less involving than it actually should.
Grado impressions
It's amazing what the Grado's manage to do here in terms of definition and PRaT. But also Jari's voice gets that lovely raspiness (an acquired taste, maybe) that the AKG's just do not convey. Everything points to one thing: this stuffs just too fast for the AKG's. The Compass is here again far and away the best and most exciting performer. For the first time you can actually hear the harp playing throughout the song, instead of just at the beginning.
DISCUSSION
This is going to a bit sloppy, because I'm still trying to interpret all the things I heard throughout trying these different samples of music. The order in which I put the different pieces is the same as the order in which I listened to them.
In the first part of the listening sessions, using all sorts of classical music (unamplified music), things really looked like they were pretty going to be reasonably clear cut. The worst performance was almost invariably by the Corda Opera solo. Combining the DAC section of the Compass with the amp section of the Corda Opera, clearly showed where the problem was. The DAC in the Corda Opera is just not very good. Actually I'm rather shocked how badly it performed with certain recordings. Reports about the quality of the Corda Opera DAC have varied throughout reviews, some calling it 'only of average quality', others characterizing it as at least the equal of the DAC section in most 500-700$ cd players. As can be seen by the design specs above, this DAC certainly was not an afterthought. Moreover, it benefits from a dedicated power supply, something the DAC in the Compass does not have. So it's rather surprising how little detail it often manages to lift from recordings. And, even worse, how often it seems to suffer from a general 'digital' glare in the upper range. Generally, the impressions in that first section also seem to point to the Compass amp being less satisfying in than that of the Opera. The Compass amp occasionally seemed to marginally best the Opera amp when it came to detail, but with regard to soundstage, separation, acoustic cues and instrument colour the Opera amp proved clearly the superior one.
It proved rather surprising towards the end to switch to recordings of amplified music. Suddenly the tables seemed almost completely turned. The Compass amp invariably outperforming that of the Corda Opera in detail, PRaT and involvement.
Well, this proved rather educational. Probably the primary difference between these two 'groups' of music (amplified and unamplified) is the far greater complexity of the soundstage information that has to be resolved in the recordings of unamplified music. But it appears that this particular element has major consequences for the reproduction of other aspects of the recording. Throughout the unamplified samples the Compass amp seemed the less resolving one, however, listening to the amplified music proved this not to be a black and white thing. It appears that the size of the soundstage an amp manages to paint has a very strong impact on the resolution that can take place in this soundstage. (Who knows, there might even be a positive effect on the characterization of instrument colour.) It's interesting to hear these things so clear featured here as trade-offs.
So why do these amps sound so different?
The mystery that is gain
One of the most striking features in the differences in specs between these amps is the gain factor. The Compass low gain is at 13 dB (that is , in the test versions, in the new version it will be 9dB). Now note the difference with the Corda Opera which has a low gain of -5dB! This appears to be a feature of all higher end stuff from Jan Meier. The Symphony has a low gain of -7dB, the Cantate has one of -9.7 dB. Many people have complained that those amps don't go loud enough with their headphones, although personally I can't imagine anyone wanting to play their 'phones at such ear-demolishing levels. However it may be, Jan Meier has not increased the gain factor in these amps because of this. So there must be a reason for it. Partially at least, this will be the lower noise floor that lower gain brings. Lower gain means less amplification of those things that you don't want amplified in the first place. But there might be another thing... Switching the gain on the Corda Opera not just effects volume, it has a huge effect on the sound characteristic. It almost completely flattens the soundstage and has a rather crude "loudness" effect on the sound quality as a whole. All in all, it sounds like a different amp. (For those doubting these impressions. Really, I assure you when you switch to high gain on the Opera you will search in vain for the sound signature you heard on low gain anywhere on the volume dial.) So if gain influences sound signature to such a degree on the Corda Opera, would it do the same for the amp of the Compass? I haven't got a clue on this one, but suddenly I get the urge of asking Kingwa for a version where low gain is set to -5dB or so.
Through all of this I've hardly said anything about the DAC section of the Compass. No doubt this is a consequence of the fact that it's much easier to write a review about things you
don't like, than about things you
do like. And that's the way it is with the Compass DAC: there's nothing not to like about it. It sounds full, detailed and (most importantly) completely natural and organic. It would be a fitting component of any DAC-amp costing up to 1500$. At its actual price it's a steal. (And that's not even considering the versatility that comes from 'opamp-rolling'.)
CONCLUSIONS
The Compass is simply amazing. It pairs a DAC that simply can't do anything wrong with a gorgeously detailed and exciting amp section. To sell such a thing at just 400$ (let alone 258$) should be illegal. The Corda Opera DAC, on the whole, can't even decently be compared with that of the Compass, the Compass DAC is so much better they're in completely different leagues. When comparing the two amp sections things become far less clear cut. The Compass being more direct, detailed and exciting with anything that doesn't really need a large soundstage, the Corda Opera rather special with anything in the unamplified domain. (But frankly, the smaller soundstage of the Compass amp wouldn't worry me too much, unless almost all of my listening would be big orchestral repertoire.)
Afterthoughts
If you think my review is much more negative in tone than that of Peete's (for example), this may be true in a way. The important difference to note here that Peete was for a large part describing his listening experience and enjoyment of the Compass. And in this way coming much closer to a description of what the Compass would be like in ordinary daily use. For my review I've just done critical listening, mainly noting down what was still wrong or left room for improvement. Don't think for a moment that I'm not enjoying the Compass immensely when I'm simply listening to music with it.
Keep in mind with all of the above, that comparison was made with both an amp (Corda Opera) that's renowned for excelling at soundstage and a set of headphones (K500) that has a soundstage just this side of the K1000. Throw the two together and practically anything else will come up short in this department in comparison. Also, I used the Earth opamp throughout the review. The Earth is known for neutrality, but not for its large soundstage. For more details on that I might experiment more in the future with Sun and Moon. (That said, the difference between the amps remains, of course, because I did test them both fed by the same Compass DAC.)
Miscellaneous impressions
I don't really like that locking Neutrik jack. There, I said it. It's not that I don't enjoy the extra security such a connection gives, but I just don't see why this is so much better than the Neutrik combo-jacks used on the Corda Opera. They seem to grip the plug just as securely and don't have that annoying red lever that you have to push all the time when removing the plug.
There actually is a noticeable hum to the power supply of the Compass. However, it's not really annoying and it's doubtful if you would ever notice it while wearing headphones. In fact, I only noticed that it was actually still audible at half a meter distance when I switched off my computer to do the review-listening.
Well, that's it for now. Constructive criticism will be appreciated.
