DAC-Preamp having these specifications?


Rather than asking for feedback about specific products, I thought I instead would ask for your recommendations of a DAC-Preamp product(s) having a desired set of following specifications:

Output Impedance: < 300 Ohms
Balanced outputs (XLR)
Unbalanced outputs (RCA)
2 or more analog inputs (RCA or XLR)
2 or more digital inputs (coaxial + optical or USB)
DAC section preferably uses discrete components over op-amps
DAC signal processing capabilities should the usual fare though need not include every conceivable format
Price: ~$2,500 or less




128x128celander
@georgehifi If a DAC-preamp manufacturer uses only an analog volume pot, then can one assume the digital domain is set for 100% output, thereby ensuring no bit-stripping arises? I’m thinking here of the Benchmark DAC3. 
If a DAC-preamp manufacturer uses only an analog volume pot, then can one assume the digital domain is set for 100% output, thereby ensuring no bit-stripping arises? I’m thinking here of the Benchmark DAC3.
Yes, no "bit stripping" if the volume is done in the analogue domain after the d to a converter. But I haven't seen this done since the old days, maybe the Dac3 is I'll look to see if it is.

Cheers George
Just had a look at what Sterophile makes of the DAC30’s volume control, and it’s a bit vague, but to me point to it being in the digital domain not the analogue as that ES9028PRO d to a converter has volume option.
As they talk about extra resolution if you use it in the top part of it’s range. And benchmark give you the options of 0db or -10db or -20db gain attention structure in the analogue domain output buffer so then it can have the volume control it the top part of the range. (This wording "could" be the reason why some think it has a normal analog volume pot.)
Stereophile:
The DAC3 HGC has another feature that, while hardly sexy, addresses a common and underappreciated problem. Is your volume control usually set above or below the halfway point? In my experience, for most systems the answer is "below"—but most systems achieve their best noise performance in the top half of their volume range for both analog and digital volume controls (though for different reasons). Also, analog volume controls exhibit their best channel-matching in that range. The DAC3 offers pads for its balanced outputs—attenuators—that can be set, via internal jumpers, to 0, –10, or –20dB. Benchmark says that when they’re in use, the DAC3 retains its full signal/noise ratio of 128dB, A-weighted. If you’re paying for 24-bit DACs and hi-rez downloads, you’d best get your noise level down to where you can hear at least some of that extra resolution, and that’s harder than you might think


They do what Wadia did by the looks of it.

Quote from Wadia

We strongly recommend that you use your Wadia 521 Decoding Computer connected directly to your power amplifier. Even if you purchased your Wadia 521 Decoding Computer with the intention of connecting it to your preamplifier, we suggest that you try direct connection to your amplifier. Many listeners are surprised by the improvement in performance over even the most expensive preamplifiers.

Optimizing the Output Level Best performance is obtained when operating the Wadia Volume Control near the top of its range. If needed, the maximum output level of your Wadia 521 Decoding Computer can be adjusted to match the overall sensitivity of your system so that the critical listening will take place with the volume control operating in near the top of its range.
The maximum output level of the Wadia 521 Decoding Computer is adjustable by means of a set of internal switches. The Wadia 521 Decoding Computer is factory set to accommodate the most common range of system sensitivity. If you find that your typical volume level during critical listening is below 65 on the volume display, it will be advantageous to use a different setting. To change the output level, consult your dealer.


BTW the DAC30 has a lovely low 10ohm output impedance and will drive anything, just set the gain setting (0,-10, -20db) so you volume is up near full for very loud and you won’t run the risk of "bit stripping" "if" it in the digital domain.

Cheers George
@georgehifi I looked at the owners manual after posting. I think you are correct about the digital domain volume control. Here is what their manual says:

“HGC is Benchmark's unique Hybrid Gain Control system. The DAC3 combines active analog gain control, passive low-impedance attenuators, a 32-bit digital gain control, and a servo-driven volume control.

“All inputs are controlled by the rotary volume control. This volume control moves in response to commands from the remote control. Analog inputs are never converted to digital, and digital inputs never pass through an analog potentiometer. Digital inputs are precisely controlled in the 32-bit DSP system. The DSP system preserves precise L/R balance, and precise stereo imaging, while avoiding any source of noise and distortion.

“Benchmark's unique passive output attenuators provide distortion-free gain reduction without reducing the dynamic range of the converter. The attenuators optimize the gain staging between the DAC3 and the power amplifier. This optimization is absolutely essential for maximizing the dynamic range of the entire playback system.”

The output impedance isn’t uniform as a function of the different passive attenuator pads:
Attenuator:      Output Impedance
0 dB                      60 Ohm
-10 dB                 425 Ohm
-20 dB                 135 Ohm





Hybrid Gain Control system
Yes that "hybrid" word says to me half digital, half analog. The the gain setting (0--10,-20db) is done in the analog and the volume is done by the ess in the digital.


The output impedance isn’t uniform as a function of the different passive attenuator pads:
Attenuator: Output Impedance
0 dB 60 Ohm
-10 dB 425 Ohm
-20 dB 135 Ohm

The output impedance isn't uniform as a product of the gain setting, not the volume control.
That’s because the gain is most probably changed via different feed back resistors of the output buffer which will effect it’s output impedance, not to worry though, they are all low enough for your active ATC speakers.
Just use good quality low capacitance interconnects to them say ( less than <100pF "picofarad" per foot) ask the manufacturer. Keep them short as possible 2-3mt will be fine

Cheers George