[yuriv]

I tried to use a Zoom UAC-2 to replace my aging E-mu 0404 USB, which doesn't have a lot of support anymore. What looked good on paper were the Burr-Brown converters and the claimed dynamic range and signal-to-noise ratio. So I ordered one and tested it. It feels solid and the build quality is really nice. It's also good for playing software instruments because of the low-latency USB 3.0 interface. And sure enough, it beats the old E-mu for on noise and dynamic range.
 

Noise levels
 

RMAA results
 
 
But look at the distortion! The converter chips can't be this bad. Sure, you probably won't hear it when playing music, but I was hoping to have this unit do double duty in a measurement rig. It looks like the analog electronics surrounding the converters aren't up to the same quality as those Burr Brown converters themselves.
 

1kHz, THD+N
 

IMD
 
 
What's worse is the frequency response of the line out. I did not find a way to defeat this peak in their mixer app:
 

Frequency response
 
There's no reason to have this in a modern audio interface, especially one that costs $250 US. So, if you're thinking of picking up one of these to make audio measurements, keep looking.

 

[HiFiChris]

Luxury & Precision L3 Pro:
 
 
No load:
 

 
 
Triple.Fi 10:
 

 
 
Various loads:
 

 
 
-> Around three Ohms and identical to the L3 as the same amp chips are used.

 

[HiFiChris]

Hidizs AP60:
 
 
Simple loads:
 

 
-> Consistent roll-off towards the sub-bass.


Triple.Fi 10:
 

 
-> Identical roll-off towards the sub-bass. The output impedance is rather around 1.5 Ohms than the stated 0.1 which is however still good.

 

 

[HiFiChris]

Cowon Plenue M2:

 
No load (digital filters):
 

 
 
Various Multi-BA loads:
 

 
-> The output impedance is stated to be around 1 Ohm which seems to be true according to the result.
 
 
JetEffect 7 settings (partially different scale):
 
BBE:
 

 
Mach3Bass:
 

 
EQ bandwidth (Q-factor):
 

 
EQ adjustments per single frequency band slider:
 

 
Extreme bass boost (BBE and Mach3Bass maxed out, various EQ bands maxed out, some treble bands adjusted):
 

 

[reginalb]

Google Pixel XL no load
 

 
I'd heard some weirdness with my Merlins, and was hoping that it was in my head, but alas:
 

 

[HiFiChris]

 
Quote:

  Google Pixel XL [...]

 
Thank you, I've added it to the overview in the 3rd post.
 
Those Google devices were never known to have a low impedance output. The first gen Nexus 7 has got a horribly high output impedance, and when I get the time to I will load the RMAA test file to my 2nd gen Nexus 7 so see how bad it performs in this regard.

 

[reginalb]

   
Thank you, I've added it to the overview in the 3rd post.
 
Those Google devices were never known to have a low impedance output. The first gen Nexus 7 has got a horribly high output impedance, and when I get the time to I will load the RMAA test file to my 2nd gen Nexus 7 so see how bad it performs in this regard.

 
Nexus 6 it was great. Outperforms both my ZX1 and my former AK300 with low impedance IEMs

 

[HiFiChris]

@reginalb
 
Do you have some loaded and unloaded measurements of the Nexus 6? I'd really like to add them to this thread. 

 

[reginalb]

  @reginalb
 
Do you have some loaded and unloaded measurements of the Nexus 6? I'd really like to add them to this thread. 

 
I didn't have input set to stereo, but here they are:
 
Nexus 6 No Load:
 

 
Nexus 6 Merlin Load:
 

 
The Merlin is a tough load. My AK300 and ZX1 both perform nearly identically to this, but with more dropoff in the treble range. Merlins are 12‎Ω.
 
by the way, I don't see them in post 3, but I did post results on the Sony ZX1 and AK300 as well. I think they're just unloaded, I'll add Merlin load graphs to them. Here is the Nexus 6 compared:
 

 
They all have a round +.5dB in the low to mid range, but above about 8k the N6 is around .25-.5dB closer to neutral than the AK300, and around .75-1dB closer to neutral than the ZX1

 

[HiFiChris]

@reginalb
 
Thanks, I have added the measurements to the 3rd post.

Yeah, I saw the unloaded measurements back when you posted them but a straight line without any load is no sorcery anymore these days, so to see what devices are multi-driver-IEM-friendly when it comes to output impedance, measurements with critically reacting loads are mandatory.

 

[CraftyClown]

What a great thread. When I get a spare moment I shall take readings from a QP1R and a Plenue S and report back.

 

[HiFiChris]

  What a great thread. When I get a spare moment I shall take readings from a QP1R and a Plenue S and report back.

 
I'm really looking forward to seeing some loaded measurements of the Questyle. 

 

[reginalb]

   
I'm really looking forward to seeing some loaded measurements of the Questyle. 

 
While I can't help you there, I did finally get around to adding loaded measurements to my ZX1 and AK300 posts: 
http://www.head-fi.org/t/800208/the-rmaa-rightmark-audio-analyzer-source-and-audio-device-measurement-thread-measurements-in-post-3-tutorial-in-post-2/30#post_12678630

http://www.head-fi.org/t/800208/the-rmaa-rightmark-audio-analyzer-source-and-audio-device-measurement-thread-measurements-in-post-3-tutorial-in-post-2/30#post_12678536
 
Alas, I won't be able to do the more interesting Merlin load for a while. I just bought a house, and we're sleeping on a mattress on the floor while we await some furniture deliveries. I use my Merlins in bed, and after listening to them, I set them on the floor. My wife stepped on and shattered one of them. 

 
Almost gave me permission to order a set of v2's, but alas, UM is going to repair them. Still I have to get impressions done, ship them to China, and then wait. So no interesting loads, as I said, for a while.

 

[CraftyClown]

While I can't help you there, I did finally get around to adding loaded measurements to my ZX1 and AK300 posts: 
http://www.head-fi.org/t/800208/the-rmaa-rightmark-audio-analyzer-source-and-audio-device-measurement-thread-measurements-in-post-3-tutorial-in-post-2/30#post_12678630

http://www.head-fi.org/t/800208/the-rmaa-rightmark-audio-analyzer-source-and-audio-device-measurement-thread-measurements-in-post-3-tutorial-in-post-2/30#post_12678536

Alas, I won't be able to do the more interesting Merlin load for a while. I just bought a house, and we're sleeping on a mattress on the floor while we await some furniture deliveries. I use my Merlins in bed, and after listening to them, I set them on the floor. My wife stepped on and shattered one of them. 

Almost gave me permission to order a set of v2's, but alas, UM is going to repair them. Still I have to get impressions done, ship them to China, and then wait. So no interesting loads, as I said, for a while.

Nooooo! I feel your pain

 

[reginalb]

  Cowon Plenue M2:

Extreme bass boost (BBE and Mach3Bass maxed out, various EQ bands maxed out, some treble bands adjusted):
 

 
Wow look at those y-axis labels! About a +21dB bass boost! Have you listened to it? Even that Mach10 bass seemed like it would muddy other frequency bands. But over 20dB of bass boost, can you even hear any other content?