EDIT

A question is raised from time to time whether one needs an external DAC or headphone amplifier for desktop computer use. I thought I address that with a set of measurements in this article. There will be more to come because unfortunately, there is no one representative computer sound performance.For this run, I will be testing my everyday laptop which is my main workhorse for a ton of work from listening tests to running my Audio Precision analyzer. It is an HP Z series Laptop that I bought 2-3 years ago at some $2,200. It has a Core i7 processor and is designed for "workstation/corporate" work as opposed to consumer.As a way of reference I thought I compare its headphone output performance to that of Topping NX4 DSD portable headphone amplifier and DAC. See its review here: https://audiosciencereview.com/foru...sd-dac-and-portable-headphone-amplifier.3507/ The NX4 DSD retails for $160.Let's start with our usual dashboard view of the HP Laptop:Starting from the right, we see pretty decent performance with nothing out of ordinary jumping out in the FFT spectrum. Distortion is 0.005% which amounts to 87 dB SINAD (signal above distortion and noise). Ranking that among recently reviewed products we get this:It actually beats the $2,400 Schiit Yggdrasil DAC.The Topping NX4 DSD pulls way ahead here with a SINAD of 104 dB.Output voltage is a problem though with an anemic level of just 0.6 volts RMS. We like to see 2 volts for a DAC let alone a headphone amp.As to add insult to injury, it has a pretty high output impedance of 17 ohms, causing its output to drop considerably with lower impedance loads:The Topping NX4 DSD runs circles around it with 2 volts unloaded output and impedance of just 0.9 ohms.Let's compare power versus distortion+noise at 300 ohm:Power output is just 1 milliwatt compared to 59 for Topping NX4 DSD. The "good" news is that it doesn't get distorted and stays competitive with Topping until it runs out of juice.Let's look at the same at 33 ohm:As usual, when we reduce the load impedance the output power goes up. Here, the HP laptop produces 4 milliwatts compared to 144 milliwatts for Topping NX4 DSD.From pure noise and distortion, the HP Z series laptop does pretty well. There are no warts and the output is pretty clean. The main issue is just lack of drive power. There simply is not enough juice to drive anything other than IEMs to high listening levels.Even with IEMs such as my Etymotic ER4 SR, I just have enough power. If the source material has low level, sometimes I can't get enough volume out of it.Of note, I have performed hundreds of critical listening tests using this laptop and my Etymotic IEMs. So the distortion and noise in general is pretty good so the need here is an external headphone amplifier, more than a DAC. But then again, the drive level is pretty low here so might as well go for a combo DAC+headphone amplifier like Topping NX4 DSD or its many competitors.: measurements of my desktop motherboard posted here: https://www.audiosciencereview.com/...ernal-dac-headphone-amplifier.4116/post-96588 As always, questions, comments, corrections, etc. are welcome.-----If you like this review,using Patreon ( https://www.patreon.com/audiosciencereview ), or upgrading your membership here though Paypal ( https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054 ).