Aiming to eliminate as many variables as possible, and because the Dacmagic does not have a headphone socket, this test is conducted as thus:
HP nc8430 -> usb -> Edirol UA-25 / Cambridge Audio Dacmagic -> RCA -> RSA Tomahawk portable headphone amp -> Senn HD600
Playback on notebook are via asio4all and Foobar. Test tracks are as in the speaker test (see link)
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Three differences were apparent and confirmed through multiple listenings [sic] of the play-list of the superiority of the Dacmagic. Just as well then as it sells for 2x the Edirol.
a) Bass volume and presence
Immediately when those notes started playing at the beginning of Fallin', the bass quantity is greater than through the Edirol. On Breathe it just fills empty spaces that you did not realise was being vacated! At this stage it is too early for me to determine how the quality of the bass has changed, even as the quantity has increased but I would tentatively say that there does not appear to be any encroachment by boominess [sic]
That is not to say in any sense, however, that the bass quantity has increased to detract from the rest of the sound or to distract. Indeed I believe the Dacmagic has more about it and can exert greater control and finesse over the music. At the same time as the repeating bassline on Breathe is playing out, the background modulating effect that begins early on in the track has more presence and forwardness about it. In the Edirol it is relegated off-stage. It is like dishonouring an important supporting act
b) Sound stage
No doubt about it, the Dacmagic certainly has a wider sound stage than the Edirol. There is just more room to play with. Where before I did not know it, different elements of the song overlapped and competed for space. Now everything is nicely balances and spaced out. And with that some of the details trickle out and the underlying elements of songs are unmasked (as above, with Breathe). Instruments now gain those little extra peaks and reach not found on the Edirol. A touch sharper, a touch more tonal structure, just a touch more realism
c) Volume
Small thing. Through the Dacmagic, I need to turn the volume knob on the Tomahawk up from 9am to 10am to drive my HD600. Amp is set to high gain
d) Mids, or rather the vocals
Wow. I do not know what to say. I want to try experimenting and see if the Technics will act as a pre-amp but I have to say the vocals are just lifted up another level. They are quite good before, but through the Dacmagic they are more of a show stopper. I played one favoured track of female ballad-ey vocals (if I knew the English translation I'd post it). By way of metaphor, where my heart rate rose through the Edirol, my heart skipped a beat when I hooked up the Dacmagic. There is just that je ne sais quoi quality now present. Heart melting
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That's my thoughts for now. I reserve judgement on whether the Dacmagic is worth the cost