DACs - another frequent rip-off; read the facts before getting phooled!

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DACs - another frequent rip-off; read the facts before getting phooled!

Post by superphool » Fri Sep 20, 2019 11:14 am

DACs - Digital to Analog Converters - as stand-alone units for headphone listening or feeding an amplifier, are a relatively new phenomenon.

They are also one of devices that has some of the most ludicrously overpriced items in the home audio or audiophile market.

A DAC is used to convert digital audio back to analog audio, to feed an analog device such as an amplifier or headphones. Anything that plays digital audio to loudspeakers or headphones from either internal storage or an external source has a DAC of some form built in.

Stand-alone DAC units are often claimed by the makers & sellers to give better quality reproduction than the built-in ones in most consumer equipment. That may be true; cheaper equipment may have lower quality or lower resolution converters and the analog stage that feeds to may also have only moderate quality and noise levels.

However, you can get truly excellent quality DACs (and ADCs, the reverse) for relatively little money.

The Focusrite Scarlett 2i2 is a good example of a superb piece of electronics at a very reasonable price:
These are capable of handling 24 bit audio at a sample rate of up to 192 KHz.

The The distortion figure (THD + Noise) is just 0.002% and the frequency response is flat from 20Hz to 20KHz within 0.1db.

In fact, these units are a full "Audio MIDI Interface" designed for connecting audio equipment to computer-based software for music production.
As well as the headphone DAC section, they contain two microphone preamplifiers with ADCs and two additional DAC outputs (or one stereo channel) for connecting to other equipment such as amplifiers - all with the same high sample rate and low distortion specifications. And MIDI ports to connect to such as keyboards or synthesisers.

Overall a far more versatile unit than a dedicated headphone DAC, though they can of course be used purely for the headphone section if that is all you need.

The cost: Around £100 ($130) new, if you shop around a bit; list price is around 140- and they can often be found secondhand at much lower prices.

Their specifications are as good or often better than many "Audiophile DACs" costing from several hundred pounds to even several thousand pounds.
One we looked at costing over £4000 has significantly poorer distortion figures and flatness over the 20 Hz - 20 KHz range.

These crazily priced gadgets seem to rely on non-technical people looking for the most expensive thing they can afford, on the assumption "it must be good at that price".

Unfortunately that assumption is often just wrong and so far we have not seen an expensive DAC that would genuinely give a better listening experience than that £100 audio interface.

Some DACs do claim much higher headphone power outputs - but why? Once the level gets beyond what you can bear, any increase is unusable and meaningless, or even dangerous.

Testing a Focusrite Scarlett 2i2 with some genuinely recording-studio grade headphones, (Sony MDR-7506), the audio level is reaching the pain threshold at about 50% on the headphone level control.
There is more than enough volume available to cause hearing damage with that unit, so what is the point of higher power outputs? They just appear somewhere between pointless and an accident waiting to happen.

As always, look carefully at the technical specifications of anything you are considering buying - they are infinitely more important than any general advertising claims.

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