I'll be honest here, the Grace m902 is on my very short-list for DAC/headphone amps, and one of the prime factors is the USB input. Competing units I'm considering are the Apogee Mini-DAC, and the hinted-at-but-not-yet-released PS Audio headphone amplifier. I've seen the new Perreaux USB model online and it doesn't seem to meet my requirements. There is supposedly a new Benchmark Media model that supports USB on the way, but I don't know that even if the DAC1 materialized a new port that it would do it for me. Probably the largest thing against the m902 is the price, but that said, I do NOT find the price out of line for what you are getting. The 902 looks like an amazing unit, it is just pushing the tolerance of my budget for this project. But we'll see, since I've been good this year.
Plus it has some unique features that the others do not, and a distinguished headphone amp pedigree so...
That said, one of my requirements is that it must be somewhat transportable, only because I can't afford three. (Work <--> Home <--> Out of town )
Certainly based on the dimensions provided, it seems to be acceptably sized to me. That picture and PDF make it look larger, but when I get out the ruler, it seems to be a quaint little size. Relative to a full-sized rack unit anyway. It seems I should be able to put the unit in a pack like the M-Audio StudioPack in the pocket normally reserved for the Ozone keyboard, perhaps with some additional padding or a sleeve case for extra protection.
Questions re: m902
What is the approximate weight? I'm guessing 3-4 lbs?
How hot does the unit run when driving normal headphones at reasonable levels? (ie. neither totally inefficient headphones, nor head-blasting volumes)
I'm assuming it is nothing to speak of. The only reason I ask is, what if one was running it from within a bag such as the StudioPack. Does the unit need to vent/breathe at all, or assume some level of ventilation?
What is the power-draw of the unit? Is out of the question entirely to power it with an external battery pack? (I note that the Apogee can accept 6-14V so in comparison is probably more flexible there) How about feeding the unit power from a standard DC-AC convertor for use in an automobile? Those types of convertors seem to range from 75W --> 140W --> 350W
I would be interested in hearing Michael describe any of the problems with respect to Mac OS X - since I would strongly like to move in that direction with my next laptop. I should note that people have noticed the Apogee Mini-DAC losing sync with their Mac's, I believe with respect to switching sampling rates from 44 -> 48. Michael's comments I believe pertained to sampling rates at 48.
As indicated, the unit would transported (gently!) in a well-padded carrier - usually in a warm car (rather than our frigid Canadian winter). I just wonder if there would be any comments if this might affect the life of the unit. The Grace products seem to me, to be of studio quality and build rather much like a tank. Would anyone disagree there? I realize that taking the unit from a cold environment to a warm one might be an issue, and like all electronics should be allowed to warm to the new environment before use. At least it's not got any tubes in it.
One point Michael perhaps with respect to the design. Does the unit have a slot for your standard Kensington lock? If not, perhaps you could consider this for buyers who do use the product in a somewhat public environment. That should add minimal cost, since it's just a little hole for the lock nub. (Then again I'm not in manufacturing, so...) And yes I realize the those cylinder locks are fairly easily defeated but every bit helps. Or how do people secure their headphone amplifiers?
Finally, who are Grace Design authorized resellers in Canada (province of Ontario, hopefully close to the Greater Toronto Area)? I am familiar with Lakeshore Music (aka Long & McQuade), but I know for a fact their store didn't actually have a 901 in stock, and likely won't have a 902 so it'd be a special order. Would there be any disadvantage to me in purchasing from an (excellent) reseller like Headroom - in terms of warranty service or otherwise?
Speaking of which - how long is the warranty?
Sorry for the barrage of questions, hoping to make a decision sometime between now and Jan 2005 sometime. Looking forward to seeing lots and lots of pictures on your website when the product is released. (hint) Getting a good sense of the product through images is very important to me, since it is unlikely I'll ever see one unless I order it.