NuForce made quite a splash when it entered the high-end arena several years ago, particularly with its switching amplifiers. The company then gradually expanded its product range downward to include $100 DACs and $500 integrated amplifiers. However, NuForce co-founder Jason Lim wanted to focus on the upper end of the market; thus, with the backing of the OEM factory, he has formed a new company, called NuPrime, to design, build, and market upper-end products that are consistent with the company’s original mission.
The IDA-16 integrated amplifier reviewed here is a good example of this shift. At $2600 the IDA-16 represents the high value for which NuForce is known, but allows for more ambitious design and implementation than sub-$1000 integrateds. For your $2600 you get a 200Wpc unit with a built-in DAC that will play just about everything digital on the market today. The IDA-16’s price is still reasonable by high-end-audio standards; in fact, depending on its sonics, NuPrime’s integrated could be an outright bargain. My job in this review is to find out if that’s the case.
I would describe the IDA-16 as a modern integrated amplifier. By that I mean it integrates the electronics most audiophiles use today: a DAC, preamp or control center, and a power amp. So all you need besides the IDA-16 is a source. (Well, OK, you need speakers and cables, too.) The DAC plays just about any computer-file format of interest to audiophiles, with five digital inputs—one asynchronous USB and four SPDIF (two on RCA coax, two on TosLink). In case a user has an analog source (like a phono system or a tape deck) there’s also a line-level analog input.
I see this type of component as the future of integrated amps; except for very high-end DACs, there’s no reason why DAC circuitry can’t be housed within an integrated amp or preamp chassis. Think of it as functionally similar to one of the Devialet amp/DAC combinations without the ultra-high price.
All the IDA-16 has to offer is packaged in a sleek black chassis with your choice of black or silver front and side panels. If I tell you the amplifier weighs 16 pounds and produces its 200Wpc with 93% efficiency, you’ll probably guess the output section is a Class D switching amplifier, and you’ll be right.
First a few details about the IDA-16’s circuit. It is based on a “self-oscillating circuit” to generate the pulse-width modulation (PWM) signal that turns the output transistors on and off. The switching frequency is a very high 600kHz, about double the speed of most Class D amplifiers. In this regard, the new switching output stage is an advance over those used in the original NuForce amplifiers. The power supply is a switched-mode type. Together with a Cross-Matrix Array (CMA) capacitor bank, the power supply can deliver very high current to the output stage on demand. (The switching power supply in David Berning’s ZH-230 tube amplifier showed me how fast such power supplies can furnish real-world current, and how important that is to reproducing the flow and dynamics of music.) Equally interesting is the precision volume control, which uses a switched-resistor arrangement wherein only a single resistor is in the circuit at each of the control’s 99 positions (divided into 0.5dB increments). The internal DAC uses the popular ESS9018 Sabre chip, while XMOS input chips are used for the USB input. OPA2134 chips are used in the analog section. Very low noise JFETs are used in the input section.
The built-in DAC is quite special, too. It plays PCM at sampling rates up to 384kHz and DSD256 (11.2MHz sampling rate). Although DSD256 is mostly a curiosity at this point, several companies now offer commercial DSD256 releases, and doubtlessly other companies will soon follow suit. (I just hope DSD doesn’t degenerate into a numbers game.)
Although at first glance, it looks like the IDA-16 is devoid of controls, there are actually six small, unobtrusive buttons on its front panel. The three buttons on the left side are used to select the input and turn the amplifier on and off. Under the buttons is a display showing which input is selected. On the right side of the amplifier are buttons which raise and lower the volume level and mute the output. A display under these buttons shows a numeric volume level as well as information about the input. For example, on a DSD256 file the input displays “d11.2,” where “d” means a DSD file is being played, and “11.2” means the sampling rate is 11.2MHz. On the black review sample I received, these buttons were almost invisible. Fortunately, all the controls on the front panel are duplicated on the remote, which has much larger buttons that are easier to operate and are clearly labeled. The remote is a black metal tube eight inches long with a hexagonal cross section. The silver buttons tend to rattle a bit, not that that’s a drawback.
On the rear panel are five digital inputs and one analog input. Outputs consist of five-way binding posts for speakers, one set of RCA jacks for subwoofers, and a TosLink digital output. A standard IEC jack provides AC power input. There’s also a voltage-selector switch for the AC power. With plenty of space between the jacks, cables shouldn’t be crowded.
The impedance of the IDA-16’s analog input is greater than 1M ohm, while the line-out output impedance is less than 100 ohms. So virtually any source equipment can drive the IDA-16, and the line-out should work with virtually any powered subwoofer or external amplifier. The manual comes on a USB flash drive, along with USB drivers for Windows computers. Of course, if you use a SPDIF input, no driver is needed, but SPDIF has limited maximum sampling rates, if that matters to you. The SPDIF input only accepts PCM files; for DSD playback, you have to use the USB input.