Mar 1, 2019

Do I need an external DAC?

Hey everyone this is my first post here! I just received a pair of HD6xx’s and a Bottlehead Crack + Speedball amp is on it’s way (it’s on sale right now but I don’t know when the sale ends.) I finally decided on this combo after reading about how great these two sound together. The only question I have is: how much difference in sound quality does an external DAC really provide and what other reasons are there for getting an external DAC vs using the built-in one like in an iPhone or Macbook Pro? Obviously the price of the DAC will answer part of that question so I’m mostly wondering about DACs in the $200-300 range. Also, I have some FLAC music but most of my listening is through Spotify with their 320 kbit/sec feature so if I don’t get an external DAC, what do you think will be the bottleneck in my setup?
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Here’s the thing: the Digital to Analog Conversion process is messy. A better DAC creates a more realistic tone (plastic imitation vs organic recreation), and often helps increase the perception of how many layers of depth you can distinguish. You will still hear the same notes, played at the same speed, but sometimes lower end DACs seem to take the energy out of certain instruments or everything in a song. First of all, a more expensive DAC is like an error-correcting computer. The process is never 100% error free, but a more accurate and better protected digital section will more realistically reproduce what was recorded in the studio. Second, many people forget the “A” section of all DACs: even if it has a fixed volume and power output that isn’t suitable for headphones or a speaker, the Analog section has an amp. Therefore, in addition to all the digital factors to consider like hitter and timing, a DAC is also subject to amping considerations like distortion, slew rate, stability, etc. You might buy a nice amp, plug it in to the MacBook Pro’s headphone jack, and still not get the subbass response you were looking for (However, the high input impedence of an external amp is about the easiest load for the MacBook’s headphone jack to drive, so you should still hear some improvement). Many Macs do have a cool trick up tgeir sleeve: a combo headphone mini jack and mini Toslink optical output port! Ask an Apple rep if your model has the Mini-Toslink optical combo port, because that will let you connect digitally and cleanly to an external DAC without using any USB ports (and not subject to the slew rate, EMI shielding, and cable quality variances of USB). iPhones since the iPhone 7 two and a half years ago don’t even have DACs accessible to headphones anymore. Inside that tiny little dongle included by Apple is actually a tiny DAC/amp combo – purchased separately, that thing is just $9, and even if Apple sells that at-cost or at a loss, that’s a TINY budget to design a DAC/amp for. It’s not completely garbage, but it is a MVP (Minimum Value Product). The DACs in older phones were a bit better (designed by Cirrus Logic, or Wolfson if you go back to the iPhone 4S), and better than the average Android. Until LG’s recent phones totally tried hard and made something equivalent to a $150 DAC/Amp combo, the audio components in smartphones were only a tiny portion of the overall design budget, much closer to Apple’s $9 dongle or less. If you imagine the capabilities of a DAC or an amp on a sliding scale, there is a lot of room to gain capability, and the costs can meet or exceed the cost of headphones, even the most expensive ones. Improving your headphone does not improve your DAC, that may sound obvious enough on paper but the headphone can only perform as well as you feed it. You could enjoy a $500 MSRP Sennheiser HD 650 (now sold on Massdrop for $200) with a $100 Schiit Modi DAC and $100 Schiit Magni amp, but that same HD 6XX will reveal even more of its potential with a $500 Chord Mojo DAC and $600 Cavalli Liquid Carbon. I started enjoying my $1400 MSRP HD 800 on that Mojo and Liquid carbon setup, but it sounds even better on the $2400 HDV 820 DAC/amp I have now! A higher price isn’t a guarantee of improved performance, just like money doesn’t buy you happiness, but a bigger budget does give the designers more to work with! Cool facts: Spotify may “only” offer 320 kbps lossy compression, but they use Ogg Vorbis instead of MP3, so it sounds a bit better! If you want to dig deeper, a better DAC is NOT about producing a higher pitched sound. Something that took me years to come across, understand, and realize there was still more to learn was that a 44 kHz signal is required to reach a 22 kHz pitch note. It is commonly quoted that “the human ear” can hear pitches from 20 Hz to 20,000 Hz (20 kHz), but by the time we are 30 years old almost everyone has some hearing loss and will lose a couple thousand Hz off the top range as our ears wear out. Nyquist Theory includes the statement that only the “peak” and “midpoint” of a sine wave 〰️ is required to recreate the correct pitch of the sound, meaning that as long as the digital file knows those points 📊 it can recreate the music. People that argue against hi-res music, saying we can’t hear anything better than CD-quality anyway, are referring to this. Now, I am not a sound engineer (I have a liberal arts degree!), just an enthusiast whose brain hurts if you feed it too much too fast, but the short version of this debate is that the CD-quality fans have a point, but since we usually listen to more complex waveforms representing multiple instruments playing at once rather than pure sine waves, the Nyquist theorem only looks at part of the big picture. Essentially, you might come across this argument against hi-res some day, but don’t worry about it too much.
(Edited)
https://www.massdrop.com/talk/341/if-you-have-a-mac-you-dont-need-a-dac Read the above thread. MY opinion? YES. You DO. Otherwise....don't spend money on a nice listening rig, unless you intend to use it solely for analogue source listening. You don't need t spend bajillions on the DAC, either. 120-150 USD will get you something nice enough to go with.