[exe163]

I am just entering to amp scene. Been a "non-believer" for a long time. One of the mystery to me still is what makes an amp sound good. For a while, I had been powering my HD6xx from my Macbook Pro. It was loud enough and Apple DAC has a reputation of being low distortion and transparent. But it just sounded a bit off. Curiosity drove me to try out the amp route. I wasn't sure how amplification would make a difference since all we are doing is amplifying the signal. My college circuit class taught me that amplification introduces some distortion but otherwise the goal is to preserve the original signal as faithfully as possible; it shouldn't affect the sound quality much, right?

After I tried the liquid spark, it was night-and-day for me despite most people claim that loud enough is good enough and "source" doesn't matter much. It's no secret that Macbook DAC or the usb-c dongle DAC are optimized for lower impedance headphones and not pair well with HD650 class headphones. Other reviews seems to echo my observation: it's loud enough but sounds tinny and not enough kick. Both the Q5K and LS amps were able to produce more impactful sound regardless of volume. What's still surprising to me is how LS sounded much fuller than the Q5K. Measurement wise, the Q5K, while not perfect, should be more than adequate; and it produces plenty of power. When compared to the LS, again it sounded tinny and not as enjoyable to my ears, even with balanced cables (more juice). What's the secret for desktop class amp that portables don't have and not show up in qualitative measurements. Q5K is certainly loud enough especially for balanced output.

Knowing that life is a comprise, it's not surprising that desktop amps sound better. For my use-case, I will mostly listen tethered to my desk. Portability and wireless are not that important to me. However, Q5K is still in the running mostly because it has mic bypass. I frequent calls and chat during gaming. Not having to run another cable just for mic improves my quality of life quite a bit. It's the same reason why I had been running without amps since with my inline mic cable for HD6xx everything just works when plugged directly into the headphone jack.


P.S. in the past, I mostly stuck with IEMs and never had to deal with hard to drive headphones.

 

[Gilles De Rais]

You’re running into the watts vs current issue. See this post on Audiogon for a reasonable explanation. https://forum.audiogon.com/discussions/watts-versus-current
In essence the desktop will ( in general) have better power management (bigger capacitors, regulated supply) than a portable and be able to provide more current when needed by a complex impedance profile.

 

[478423]

Unfortunately as you have learned (and I also learned this when I had the HD650) that loudness does not equal distortion free or no room for improvement. Both ohms and the sensitivity matters. The HD6xx series (all three) have high sensitivity and high impedance. When powering these, it's important to note both for the reason you said: The MacBook and dongles are more suited for headphones with high sensitivity and low impedance. Most people that use dongles and plug straight into the jack do not use high impedance headphones, so they are more geared towards the general populace.

I personally don't use desktop amps because I can't keep still at a desk long enough to warrant that.

 

[exe163]

You’re running into the watts vs current issue. See this post on Audiogon for a reasonable explanation. https://forum.audiogon.com/discussions/watts-versus-current
In essence the desktop will ( in general) have better power management (bigger capacitors, regulated supply) than a portable and be able to provide more current when needed by a complex impedance profile.

Ah I see, this makes sense. Ironically, the Q5K publishes HD600 current and power usage at different sound levels: https://docs.google.com/spreadsheet...8VTiP_5oiFR_WMQTYjngyHrsls/edit#gid=374902692

On paper, this should drive my HD6xx more than adequately. So I tried pushing them to close to the dac/amp's peak voltage level hoping that it would release more stable current while lowering my system volume to compensate for end loudness. The sound ended up sounding very distorted and even more thinny and out of breath. I suppose despite this unit's peak 240mW (on balanced, according to spec sheet) simply not sufficient. The Liquid Spark in comparison can output 2.4W peak.

Unfortunately as you have learned (and I also learned this when I had the HD650) that loudness does not equal distortion free or no room for improvement. Both ohms and the sensitivity matters. The HD6xx series (all three) have high sensitivity and high impedance. When powering these, it's important to note both for the reason you said: The MacBook and dongles are more suited for headphones with high sensitivity and low impedance. Most people that use dongles and plug straight into the jack do not use high impedance headphones, so they are more geared towards the general populace.

I personally don't use desktop amps because I can't keep still at a desk long enough to warrant that.

I am curious whether you were able to power your HD650 well with a portable amp. I know that Q5K and devices of its class are weak even for the a portable amp. While portability is not a major concern of mine, having a small factor and being able to power off of usb without external power does make life easier. I wonder if there are other portable amps without using wall power that can provide similar sound quality to the Liquid Spark or other $100 desktop amp.

 

[Gilles De Rais]

I suspect in respect of the HD650 and driveability the answer is transportable (Romi, Cayin C9, Woo WA8 or WA11, ifi Micro and Diablo- all comfortably over $500…) probably, portable (usb dongles and the like) probably not. Its all about current delivery. TBH i only drive my 650 from a Naim DAC V-1 with its dedicated Class A head amp. Not even the ifi Micro Black lalbel gets a sniff of her…

 

[exe163]

With that those price tags I can rest easy that the desktop amp route is the optimal and only path for me.

While we are on this topic I might as well get this confusion out of the way as well\: what's the point of having a (expensive/good) desktop DAC? I already have the understanding that DAC at best already hits the law of diminishing return after transducer and amp. I see the budget crowd rave about the Apple "dongle DAC" for having low distortion measurements, low cost, readily available, and simple (built-in for the Macbook). But most reviews also conservatively claim that it can match mobile DACs at around $100 range. It again begs the question: what advantage does it give for a desktop grade DAC and how does more expensive DAC improves the sound quality. This step seems a bit more straight forward: convert bit (most of the time already lossy) into analog signals as closely to the encoded source as possible. If one wants different character or sound, this should've already been done at the amp stage where there's more leeway to amplify different frequency with different magnitude. What's left is the most accurate representative of the bits, usually done by a nail size DAC chip. Then how come the audio industry can make this into a laptop size device device. Or, marketed it as having synergy to amp of the same class (e.g. Atom, Schiit stacks).

P.S. my undergraduate electrical engineering degree did not prepare me well to answer these hard questions. It seems like we are getting into the arts territory.

 

[CharlyBrown]

I second what the others answered. Your desktop amp is not better over all, It’s just better suited for the use-case with your 300 Ohms over-ear headphones. The 5k on the other side will handle alls IEMs perfectly well and it has other capabilities than just amping. Through It’s companion app it offers pretty much the best in class EQ and a ton of other features.

The other way around, if you compare your desktop amp and the 5k with IEMs or easier to drive over-ears, there wouldn’t be much of a difference.

 

[Gilles De Rais]

Speaking as someone with two history degrees, arts territory it is…
I think the issue with DACs is that people tend to concentrate on the ‘digital’ and not the ‘analogue’ side. Crafting a decent DAC is more than just sticking an ESS, AKM or Burr-Brown in a box with an i/v converter and an op-amp. Its the engineering after the signal leaves the chip that makes the audible difference. One of the things that annoys me is the idiots who say it is just one and zeroes…
You mention Schiit - ask yourself why there is price differential (and box size differential) as you move up from the Modi to the Yggdrasill. Looking under the lid shows much more complex engineering.