DAC / AMP - Clarifications

[chiller15]

I'm looking at my audio setup and I'm not sure I fully understand it fully to make a decision on things.

 

I have an ASUS TUF Z390M-PRO Gaming WIFI and a pair of cheap Creative T10 2.0 speakers. When using headphones (Sennheiser HD 599 SE), I am plugging them into the headphone jack on the speakers. Am I right in thinking that the motherboard's rear IO is the built-in DAC and the speakers are an additional amplifier in that scenario?

 

I don't get any nasty audio quality (at least to my ears) such as hisses and stuff from them, so I'm not sure if an external DAC is necessary? Or if I got one, I presume the perceived difference would be minimal to my non-audiophile ears?

 

My other questions are regarding plugging the headphones into other peripherals:

• If I connect my PC to the TV (LG C1) over HDMI, which transmits the video and audio over HDMI...if I plug the headphones into the headphone jack on the TV...is that using the same DAC as the on-board audio, or does my TV deal with both the conversion and amplification then?
• I have the same question regarding plugging into my Xbox One controller via it's headphone jack, when I have that connected wirelessly via the Xbox Wireless Adapter for Windows
• What about connecting via the front panel audio jack? Does that route through the same on-board DAC, or is that a separate, crappier thing?

 

I hope that all makes sense?

[kennyfs]

1. External DAC is great. You can start with a cheap one, maybe US$30. I personally get a significant better experience with an external DAC.

 

2.HDMI only transmits digital data, so it should be using the TV's builti-in DAC.

 

 

[mariushm]

The sound card on your motherboard is a Realtek ALC1200 (S1200A is basically a rebranded ALC1200)

The sound card has a built in  DAC for the stereo-out  with up to 110dB SNR (signal to noise ratio) ... this is a decent value. 

The chip has 3 headphone amplifiers which are specified up to 30mW on 32 ohm impedance. Your headphones are 50 ohm , which are close enough that you wouldn't feel a significant decrease in audio quality of volume, the internal headphones amplifier can handle your headphones. 

 

The ALC1220 bumps up to SNR to 120 dB and has better headphones amplifier, one of the amplifiers can handle up to 600 ohm impedance headphones and works in a special way that doesn't need capacitors on the output, which results in less pops and distortions, so overall quality would be better if you truly have great headphones.

 

Anyway... the analogue sound that comes out the onboard sound card goes into the T10 speakers, where there's an audio amplifier chip which amplifies the signal to be able to drive the speakers. 

The quality of the sound you get in the speakers will depend on how well the audio coming into the speakers is shielded / insulated from the electrical noise generated by the power supply inside the speakers (required to power the amplifier chip), and audio quality is also affected by the components used around the amplifier chip, the amplifier chip itself and the quality of the speaker case.

So your sound card may output nice clear sound but the moment the sound goes into the stereo in jack on your headphones, it could go from nicely shielded stereo cable to 3 traces on a circuit board which could pick up noise from a poor quality power supply for the chips inside the speaker. 

 

Luckily, they're Creative speakers, not some noname crap, and at least they're trying a bit by having the power supply outside the speakers (I see in pictures the speakers have a DC in jack) so the noise of the power supply is away from the actual amplifier chip and analogue signals. 

But even so, the speakers are just average ... they list 80dB SNR, only claim 80Hz and higher.. no THD values specified, they're not meant to be great speakers. 

 

When you plug the headphones in the headphones jack, either it's a pass through, connecting the headphones directly to the audio input of the speakers, or the amplifier chip in the speakers has a separate headphones amplifier for them. 

You could probably figure that out by connecting a stereo cable from the headphones output to the line in of your pc and record something and compare that with the same sound you record by routing the stereo out to line in directly. 

 

[chiller15]

Thanks for the replies, I was thinking along the same lines, but my technical knowledge on the subject is quite limited and I've now got a lot more understanding. I've added an additional question into the original post, to question the front panel audio connector.

 

So plugging the headphones into the speakers shouldn't particularly reduce the audio quality compared to directly into the motherboard? The speakers are on the crap end, but I rarely use them. Usually it's headphones or the TV's speakers.

 

I simply can't afford at the moment to go all out on a nice audio setup...so I'm just trying to make best use with what I've already got at hand.

[mariushm]

You'd probably get better quality if you plug your headphones directly in the connector in the back of your computer. 

That output is slightly better quality than the front panel headphones output usually, but even that front panel header is often decent enough quality. It depends on how the case is built and what cable is used for the front panel audio - some cases use a flat ribbon cable which could pick up electric noise from inside the case, other designs use have cable with those audio wires shielded with a copper or aluminum mesh to protect the signals (like a coaxial cable).

 

If you want to use the stereo output in the back, you can buy extension cables so that you don't have to constantly bend in the back.

Here's an example that sounds like it has the right shielding and everything, so it wouldn't degrade the signal : https://www.amazon.com/FosPower-Extension-Adapter-Connectors-Motorola/dp/B01553FCLI/

So then you can plug your headphones directly into the jack on your desk. 

You could use a splitter to connect the speakers and have an available connector for your headphones, so the headphones won't go through your speakers and could power off your speakers completely. Here's an example of such splitter: https://www.amazon.com/Headphone-Splitter-Syncwire-Nylon-Braided-Stereo/dp/B07431YDWM/

 

 

[chiller15]

Thanks again, I'll look into those.

 

What about having the headphones connected to the jack in the TV or controller? Would that be a significantly worse audio experience?

[OfficialTechSpace]

Better headphones would be more beneficial than an external DAC/Amp solution is this case. The HD599's are a C-tier can and getting old (in terms of Sennheiser's drivers/driver technology, not the actual release date of the can). That's not to say you wouldn't benefit from an external solution however. Typically you look for DAC/Amps that are able to subdue distortions below the audible range, along with any noise. Using your onboard audio they're well within the audible range, and you won't have a lot of clean dynamic range by comparison.

[ShearMe]

18 hours ago, chiller15 said:

Am I right in thinking that the motherboard's rear IO is the built-in DAC and the speakers are an additional amplifier in that scenario?

If the headphones can get loud than max volume on just the motherboard, then the speakers are definitely acting as a headphone amp. 

If the volume knob controls the headphone levels, that could just be attenuation and the port is just a pass through.

 

 

 

18 hours ago, chiller15 said:

If I connect my PC to the TV (LG C1) over HDMI, which transmits the video and audio over HDMI...if I plug the headphones into the headphone jack on the TV...is that using the same DAC as the on-board audio, or does my TV deal with both the conversion and amplification then?

The TV converts the digital audio off the HDMI into analog using an internal DAC (Digital to Analog Converter). An amplifier is technically always needed after a DAC, but there's no telling how that circuitry is actually handled inside any given TV.

 

 

 

18 hours ago, chiller15 said:

I have the same question regarding plugging into my Xbox One controller via it's headphone jack, when I have that connected wirelessly via the Xbox Wireless Adapter for Windows

Yes, the controller has DAC/amp circuitry to provide analog audio.

 

 

 

18 hours ago, chiller15 said:

What about connecting via the front panel audio jack? Does that route through the same on-board DAC, or is that a separate, crappier thing?

Same DAC. Some motherboards have an additional "headphone amp" for the front panel connection.