The NuForce DDA-100 DAC/amp (sort of, see below) has just hit the market. It handles digital audio for speaker systems, but not headphones, so it won't be of interest to everybody here. For others, it will I think be very interesting.
The DDA-100 is a Class D "direct digital amplifier." It's not in fact a DAC/amp, with a DAC section handling D/A conversion and feeding an analog signal to an amp section. All signal processing, including volume control, is handled digitally and then applied to modulate the amp output. The D/A conversion is thus, as NuForce puts it, accomplished "at the speaker posts." So it's in fact a "power DAC" or a "digital amp" or something along those lines. That's why there's no headphone section or output - the audio signal begins with the full amp output. Advantages, in principle, are simplicity, short signal paths and the like, and efficiency. 6Moons breaks it down further and shows some internals:
This digital Class D technology has been around for a while, but not widely, and as I understand it only in much more expensive applications (I believe the lowest cost unit after the NuForce is the NAD C 390 DD, at about $2500.00). The DDA-100 is $549.00 It has one USB, one coax, and two optical inputs. The USB handles up to 96/24, the coax up to 192/24. Output is 50wpc. NuForce has said elsewhere in on-line discussions that this power level allowed them to hit a sweet spot in the design that permitted high-quality implementation at a relatively low cost.
It's small and simple, with on/off, source, and volume all handled by one knob. The source and volume are displayed on the front in red. Here it is in my living room:
I've had it burning in for about a day now. I'm not an audiophile, but I'm very sensitive to sound quality: I like clean, with lots of detail and separation. My normal home system is Red Wine Audio gear, the latest vesions of the Isabellina DAC and Signature 30 amp, with some careful tube rolling to get the sound where I want it, feeding Omega speakers. Source is usally a PC running JRiver via an AR-T Legato SPDIF converter. It's by no means the highest-end or fanciest setup, but it sounds great: I've had guests stop dead in their tracks when the music comes on.
The DDA-100 absolutely plays in this league. It's not as warm as the RWA setup, but in every other way it's as good or better (and that may be better, if you don't like the tube sound). Soundstage, placement, separation, tone, and clarity are all outstanding. I've never heard anything this good out of anything remotely near this price. By any standard this is very high-quality sound; at the price, it's fantastic. I got this unit to audition as part of a system I'm building for a family member, but I'm not sure I'm going to let it go. I'll be very interested in what others hear, but I'm really impressed.
A few other points. I don't have much high-res material, but the USB input handled some HD Tracks files without any trouble, and they sounded even better. It's happy with the Legato - it's hooked up but out of sight in the picture above - but I can't say yet how much difference it makes in this configuration. The USB input works with the iPad and camera connection kit, which is nice.
My one issue so far is a substantial speaker thump at power-on and power-off. NuForce says it's normal and OK, but my own personal jury is out for a bit.
EDIT: After living with this unit for a while, I withdraw my concerns about the thump (which is power-off only unless you cycle the amp quickly). It's there but it's not going to hurt anything.
Edited by barbes - 8/21/12 at 4:51pm