Hi Xavier,
A couple of things...
I've owned both the Proton and the Cosecant -- with both the high-res and NOS dac modules, and the cosecant is way better than the proton, but that doesn't mean the proton is a bad dac. Also, neither of those live here anymore because I was able to do a side-by-side comparison with my current dac, and again, there was no contest.
With regards to processing power, there is actually a point of diminishing returns as once you have enough power to move bits out the door (and this can be easily improved with any given computer by shutting down background process and other things that could grab the processor's time), any processing power above that is just additional RF energy that invades the circuitry and has the potential tointerfer with the signals. Also, with laptops, you can never get too far from the display hardware, and this seems to be one very large contributor to digital noise and interference, again lowering the quality of playback. I run the Mac mini headless and use a remote app on an iPod touch to control it, which also lets me turn off the bluetooth and IR ports, which add another step in improvements. This stuff is criticaly sensitive to absolutely everything, and especially the AC power fed to the entire digital chain, the cablinhg -- there's a huge variability in quality to be experienced with different usb cables, firewire cables, etc. If I had not done these experiments for myself, I would be skeptical as any normal engineer would be.
Increasing memory is typically a good idea, but again, only if your playback software can support truly track-buffered memory play, which most sofware out there can't do. The speed of the external HD is also another factor, and the 5400 rpm drives typically sound better than the faster 7200 ones, and the firewire chipset in the drive can also have a pretty noticeable effect, with the Oxford 934 chipset being the current go-to unit.
So, the point here is that it's great that you did a comparison, I think if you're going to compare a sota turntable and R2R unit to a computer-based dac as source, you really should strive to do more of an apples to apples comparison. Of course, I can understand why you can't do that as this stuff, at this level, whilee not cheap, is typically not as expensive as a similar level TT or R2R setup.
I have been underwhelmed by most dacs, even expensive, high-res ones for years, but for me, the major concen was the convenience of access to my music, which as a blind person, and a sizeable music collection, was getting unmanageable.
It was less than a year ago now when the predecessor to my current dac came out, and that's when things really started to happen. I've played with windows boxes of various kinds from laptops to htpcs, to single-board linux boxes (very, very good and quite inexpensive) and finally in October, I took the plunge and joined the mac world and that was the quantum leap to the entire system that took it up to a level where I am now, which is further than I ever expected to be, regardless of source type.
Friends come by and listen, some very hardcore audiophiles with nothing but analog setups and are simply stunned to silence, especially the ones whose systems cost more than an order of magnitude more than mine. When that happens, all I can think is that I must have done something right -- if the people who have been fairly critical of my system (as polietely as possible) leave here shaking their heads, well, maybe I finally feel vindicated :-).
So there it is -- a computer, usb dac (16/44.1 only), a custom LDR attenuator, a pair of 3 watt direct-coupled amps, and a pair of speakers with 8 inch main drivers and a ribbon tweet, copper cabling, no power conditioning (yet) and I'm living large.
Best,
Jim
