A rant: combined DAC+HP amps

[tcpip]

Be warned: this is a rant.

Why don't ALL combo devices provide a pair of analog in/out sockets, and a 4PDT switch, so that the device can be used as just a DAC or just a headphone amp?

I know some of them provide a DAC-out. I remember the ancient Objective DAC + O2 amp in a single chassis used to have analog output sockets, but this was a DAC out. I believe some modern combo devices too have this. But very few of them have an analog in. I believe some portable devices have the analog in. Why don't all?

How much would it cost to add this? A switch to select DAC-out or HPamp-in, and one pair of sockets.

This is so frustrating. This is like having a car but without the ability to roll down the windows, or having a notebook and pen which allows you to write in only one script. Why??

End of rant.

 

[JIW]

Be warned: this is a rant.

Why don't ALL combo devices provide a pair of analog in/out sockets, and a 4PDT switch, so that the device can be used as just a DAC or just a headphone amp?

I know some of them provide a DAC-out. I remember the ancient Objective DAC + O2 amp in a single chassis used to have analog output sockets, but this was a DAC out. I believe some modern combo devices too have this. But very few of them have an analog in. I believe some portable devices have the analog in. Why don't all?

How much would it cost to add this? A switch to select DAC-out or HPamp-in, and one pair of sockets.

This is so frustrating. This is like having a car but without the ability to roll down the windows, or having a notebook and pen which allows you to write in only one script. Why??

End of rant.

If a DAC/HPA has no line-out, the HPA can be used as line-out if it has high enough level. Other than some dongles which DACs cannot produce levels high enough?

Adding analog inputs to a DAC/HPA complicates signal flow a fair bit beyond adding components. Having a switch before the headphone amp and line out is one thing. Volume control is another. A lot of DAC/HPAs use digital volume control. How is volume control to be done on the analog input? Should it be digitised and fed through the DAC? Should the volume control switch from digital to analog depending on the input? How is that to be done? Should all volume control be done analog? This may well put off those who look for digital volume control and allows no remedy for lacking headroom in the oversampling filters.

I could also complicate this further by asking why all DACs do not have symmetrical line output as well as AES-3 and IIS input and masterclock input and bluetooth and LDAC and DSD and MQA decoding because someone somewhere might want to use just that at some time. This is just features but output levels and power are another thing. Why should those not be set to some given levels judged to suit every imaginable need?

Really, what is so bad about using several devices that each have their own specialised use case rather than trying to squeeze all use cases into one device?

 

[tcpip]

Look, you make sense. I just wanted to rant, just because I wish to sometimes use a good combo device connected to the output of my phono preamp, to listen using headphones. I'm sure rants are pretty idiosyncratic.

And your point about volume control is valid, even if I don't want any of those output formats, etc. If the DAC is being used for volume control then the designer will have to abandon that and put an analog volume control to the HPA to cater to ranters like me.

 

[JIW]

Look, you make sense. I just wanted to rant, just because I wish to sometimes use a good combo device connected to the output of my phono preamp, to listen using headphones. I'm sure rants are pretty idiosyncratic.

And your point about volume control is valid, even if I don't want any of those output formats, etc. If the DAC is being used for volume control then the designer will have to abandon that and put an analog volume control to the HPA to cater to ranters like me.

The Benchmark DAC3 HGC has analog inputs but costs $2399.

You can also use a headphone amp with several inputs - one for the DAC and one for the phone preamp.

The designer could also use an ADC on the analog input and connect that to the DAC.

 

[Jimbob54]

I find it better to think of such devices as dacs with bonus headphone amps rather than headphone amps with only digital inputs.

You are in interface territory after that. Which tend not to be the best headphone amps as a rule .

 

[tcpip]

The Benchmark DAC3 HGC has analog inputs but costs $2399.

You can also use a headphone amp with several inputs - one for the DAC and one for the phone preamp.

The designer could also use an ADC on the analog input and connect that to the DAC.

An ADC is a lot of extra circuitry. I was talking about just adding an analog in/out (a single set of sockets for double duty) and a switch. But I realised, from @JIW comment, that sometimes this may not be very simple, the DAC's built-in volume control may be being used for the HPA.

And I was not talking about high-end and expensive devices like the DAC3 or the RME ADI2 Pro FS which have everything. I was talking about the JDS Element, the Topping DX series, and similar less expensive items.

 

[AnalogSteph]

I find it better to think of such devices as dacs with bonus headphone amps rather than headphone amps with only digital inputs.

Indeed. In an extreme case this can be simplified to basically a 2-chip solution, 1 USB receiver (e.g. XMOS) and 1 CS43131 or similar in a dongle.

The species "desktop headphone amp with built-in DAC" still exists but you have to look a bit harder. There's the FiiO K7 and K5PRO, and the Schiit amps with modular DAC option.

 

[Vincent Kars]

I ditched the last analog source in 2008...

 

[tcpip]

Indeed. In an extreme case this can be simplified to basically a 2-chip solution, 1 USB receiver (e.g. XMOS) and 1 CS43131 or similar in a dongle.

The species "desktop headphone amp with built-in DAC" still exists but you have to look a bit harder. There's the FiiO K7 and K5PRO, and the Schiit amps with modular DAC option.

Wow, thanks, the K7 and K9 seem to have what I was ranting about.