Need to replace my S.M.S.L SU-1 with a DAC w/ volume control

[Pauli]

My current setup results in the SU-1 delivering a pretty loud line output signal. As a consequence I can hardly turn up the volume of my amp to any noteworthy degree.

What DAC w/ volume control (by remote control and or physical dial) would you recommend? As with the SU-1 I want DSD and MQA support. And of course I need to be sure to choose a device whose volume control does affect the line out signal, not just any headphone jack that may be on board (though I don’t actually want one).


Thanks!

 

[staticV3]

A compact DAC with volume control and DSD+MQA support: SMSL C100.

 

[evalrat]

I use small DIY attenuators for that purpose. It doesn't have to nice because its hidden behind your amplifier or thereabouts. Parts cost under 20 euro's. You could also use something like a schittt passive preamp when the impedances match. This one is 8 x 5 cm,

 

[Pauli]

I’m also considering S.M.S.L D-6s.

In any case: Can I be sure that the volume control affects DSD und MQA playback also?

 

[staticV3]

In any case: Can I be sure that the volume control affects DSD und MQA playback also?

I think so, yes.

SMSL, Topping etc. tend not to dwell too long on perfecting their products' UX, but the volume control suddenly turning off just because the user switched formats, could easily damage speakers and their customers' hearing.

That would be too big a hazard to overlook, even for SMSL.

Certainly DACs exist where you can turn the volume function On or Off in the menu, but I have never heard of one where this is format specific.

Volume control is either on regardless of the audio format, or it's off regardless of the format.

And if your DAC has no such Option in the menu, then you can safely assume that volume control simply cannot be turned off.

 

[phofman]

IIUC that DAC has only cinch analog outputs. All you need is to reduce the output level - I would get/solder a trivial cinch fixed attenuator for each channel and stick it on the amp side.

 

[Pauli]

@evalrat and @phofman:

I have no experience with such devices. Will do some research though. Seems that I need a volume reduction by at least 25 dB.

 

[phofman]

It's just a cinch with a voltage divider = two resistors inside. I would not even call it a device

 

[Pauli]

I will abandon the cinch fixed attenuator idea. Fears are too strong that the DAC’s analog output may suffer from it more than necessary.

Even my »AI consultant« says so

 

[phofman]

How specifically does the DAC analog output suffer from an attenuator of e.g. 5kohm input impedance? Simple integrated amps have the same attenuator at the front - a potentiometer.

 

[Pauli]

Simple integrated amps have the same attenuator at the front - a potentiometer.

Which would result in two potentiometers my »holy« audio signal has to pass through

 

[phofman]

I would much prefer trasferring a 2V signal from the DAC over single-ended cables and attenuate them to 200mV for the high-gain amp right before the input potentiometer, than transferring 200mV over the same line. Both cases will collect the same noise in the cable line, just the first one will have it attenutated 10x by the input divider. Of course ideal would be decreasing the amp gain, not attenuating the signal, but decreasing amp gain by 20dB while keeping it stable would likely require a complete redesign of the device.

The signal passes through countless components and the two extra resistors make absolutely no difference to distortion.

But your fight...

 

[evalrat]

I have documented the internal wiring on the face plate of the box. I have several with different potentiometer values. The output impedance of the DAC is stated to be 47ohm so you can use a potentiometer as low as 1 Kilo ohm , the input impedance of the amplifier will be 10 kilo ohm or higher With a 1k potmeter there will be no loss.

 

[Pauli]

[...] the input impedance of the amplifier will be 10 kilo ohm or higher

Specs say 23 kOhm.

I wonder how to do the correct calculation here. As I said, it seems I need a volume reduction of about 25 dB, maybe more.

 

[Pauli]

Based on the amp’s volume knob:

• Rotation range is from Min=7:00 o'clock to Max=17.00 o'clock

• Top average listening position: 9:00 o'clock

What I want is a top average listening position of about 12:30 o'clock

 

[staticV3]

I wonder how to do the correct calculation here.

Buy a cheap multimeter

Play a 60Hz sine tone

Measure output voltages from your DAC and Amp.

Calculate the voltage gains, then you know how much volume reduction you need.

12:30 o'clock etc is useless.

 

[evalrat]

The exact reduction isn't important when you use a potentiometer, (Buy a logarithmic one!). Simply try an other source and match the sound level from your DAC.

@Pauli@ It looks like you're not keen on a project. If the price of the schiit really is $49 then it is a no brainer to simply buy one.

 

[Pauli]

Measure output voltages from your DAC and Amp.

With the amp’s volume knob turned to the position I want it to be? I would need to wear hearing protection for that or to disconnect the speakers.

 

[Pauli]

If the price of the schiit really is $49 then it is a no brainer to simply buy one.

I’ve ordered a S.M.S.L D-6s now instead.

 

[staticV3]

With the amp’s volume knob turned to the position I want it to be? I would need to wear hearing protection for that or to disconnect the speakers.

Well, since you bought a DAC with volume control, simply set its volume control all the way to the minimum, set your Amp's volume knob to the position you'd like it to be centered at, then slowly turn up the DAC's volume until you feel you've reached regular playback loudness.

Then you can leave the DAC's volume where it is and adjust up or down with the Amp's volume knob.

Or just leave the knob where it is and keep using the remote control, if that's more convenient for you.