[size=large]Introduction.[/size]
So far, the DAC in the m902 is a definite improvement over the one in the 901. Better than my RME 96/8 PAD as well. (this was to be a minimum requirement for me. )
I will save sound quality impressions for later, after I've lived with the m902 for awhile.
Til then, enjoy the pr0*.
Little foot can be removed by simpy unscrewing. My unit came with the feet not installed. There are little rubber feet included, but if you can, use the bigger feet, they look better and allow more clearance for cooling the bottom of the case.
Attention to detail, one area where the screwed in top meets the frame has the anodization stripped off to make conductive contact.
The Toroid has grown considerably since the 901.
Take a look at the Grace 901 for comparison.
Notice that the unbalanced inputs are now separately wired (and switched) from the balanced inputs.
Notice that the Bottom of the case, in fact the whole case acts as a heatsink now. The m902 operates more warmly, but not uncomfortably hot. This is due to the better heat dissipation.
[size=large]Possible Issues.[/size]
One thing about the USB input. I can hear a slight "click" sometimes when switching applications. Also right before music starts playing and the m902 locks the signal and the "S-Lock" lights up. But after it has a lock, no more clicks. Mind you, this is a very quiet sound. Occassionally I've seen the S Lock lose it's lock, the light went off, and there was a small "skip" in the music. This was quite rare. I only saw it once, so it may be a fluke, or perhaps an error in the encoded file. I'll have to check again.
For the DIY, you may be interested that the m902 uses the Switchcraft 1/4" Panel Mount jacks (Digikey# SC1107-ND).
While Grace Design claims them to be an upgrade from the previous jacks used before, I personally think they were picked mainly for their compact size, rather then purely for quality. While they are decent, their contact pressure is almost too weak. But at least it's not the death grip of the 901's jacks before (Neutrik Jacks?). So personal preferences abounds here, and will probably not bother anybody unless they open up their m902. Of course, I only find this an issue with my ridiculous silver K1000 adapter cable.
Also, the power button is not recessed like the 901. This means that it is entirely possible to accidentally turn the power on or off. Not something you'd expect to see for a piece of pro audio equipment. But it's a minor issue. Just watch your hands.
A thinner bezel matching the ones on the headphone outputs could solve this "problem", but I like the cleaner look.
Of course everything else is impressively sourced and assembled.
Measuring DC Offset.
0.001VDC DC for both Left and Right Outputs. Nice.
-0.001VDC for Grace 901.
So basically they're off the scale for my wimpy DMM.
[size=large]Interesting features.[/size]
You can loop out unbalanced output AND headphone at the same time. By toggling the rotary encoder (volume knob), you can adjust the volume of the preamp output separately. So, you can have another amp hooked up and control the volume independantly from the m902's built in headphone amp.
Because the m902 does not use a stepped attenuator like the 901, the microprocessor controlled volume has much finer steps than the 24 (+hi gain, so, sort of like 48 steps) that the 901 has. There is an option to increase the gain to be able to ramp up the volume faster. (This is a must for the K1000's).
The benefit with extremely sensitive headphones like the Sony R10's is that no longer am I stuck with 4-5 levels of volume adjustment.
Using the m902 as a Preamp will also have benefits of having much finer volume control with a more powerful amp like say a Dynahi.
And last but not least, a little m902 and 901 comparison pics.
-Ed
So far, the DAC in the m902 is a definite improvement over the one in the 901. Better than my RME 96/8 PAD as well. (this was to be a minimum requirement for me. )
I will save sound quality impressions for later, after I've lived with the m902 for awhile.
Til then, enjoy the pr0*.
Little foot can be removed by simpy unscrewing. My unit came with the feet not installed. There are little rubber feet included, but if you can, use the bigger feet, they look better and allow more clearance for cooling the bottom of the case.
Attention to detail, one area where the screwed in top meets the frame has the anodization stripped off to make conductive contact.
The Toroid has grown considerably since the 901.
Take a look at the Grace 901 for comparison.
Notice that the unbalanced inputs are now separately wired (and switched) from the balanced inputs.
Notice that the Bottom of the case, in fact the whole case acts as a heatsink now. The m902 operates more warmly, but not uncomfortably hot. This is due to the better heat dissipation.
[size=large]Possible Issues.[/size]
One thing about the USB input. I can hear a slight "click" sometimes when switching applications. Also right before music starts playing and the m902 locks the signal and the "S-Lock" lights up. But after it has a lock, no more clicks. Mind you, this is a very quiet sound. Occassionally I've seen the S Lock lose it's lock, the light went off, and there was a small "skip" in the music. This was quite rare. I only saw it once, so it may be a fluke, or perhaps an error in the encoded file. I'll have to check again.
For the DIY, you may be interested that the m902 uses the Switchcraft 1/4" Panel Mount jacks (Digikey# SC1107-ND).
While Grace Design claims them to be an upgrade from the previous jacks used before, I personally think they were picked mainly for their compact size, rather then purely for quality. While they are decent, their contact pressure is almost too weak. But at least it's not the death grip of the 901's jacks before (Neutrik Jacks?). So personal preferences abounds here, and will probably not bother anybody unless they open up their m902. Of course, I only find this an issue with my ridiculous silver K1000 adapter cable.
Also, the power button is not recessed like the 901. This means that it is entirely possible to accidentally turn the power on or off. Not something you'd expect to see for a piece of pro audio equipment. But it's a minor issue. Just watch your hands.
Of course everything else is impressively sourced and assembled.
Measuring DC Offset.
0.001VDC DC for both Left and Right Outputs. Nice.
-0.001VDC for Grace 901.
So basically they're off the scale for my wimpy DMM.
[size=large]Interesting features.[/size]
You can loop out unbalanced output AND headphone at the same time. By toggling the rotary encoder (volume knob), you can adjust the volume of the preamp output separately. So, you can have another amp hooked up and control the volume independantly from the m902's built in headphone amp.
Because the m902 does not use a stepped attenuator like the 901, the microprocessor controlled volume has much finer steps than the 24 (+hi gain, so, sort of like 48 steps) that the 901 has. There is an option to increase the gain to be able to ramp up the volume faster. (This is a must for the K1000's).
The benefit with extremely sensitive headphones like the Sony R10's is that no longer am I stuck with 4-5 levels of volume adjustment.
Using the m902 as a Preamp will also have benefits of having much finer volume control with a more powerful amp like say a Dynahi.
And last but not least, a little m902 and 901 comparison pics.
-Ed
