Physical placement of DAC

[pusillum_furem]

Hello all. I have a question about the physical placement of a DAC on one's desktop (especially vis-à-vis one's computer).

I have an RME ADI-2 DAC which I will be using with a Mac Mini as its sole source. I have two options for placing it on my desk: stacking on top of the Mac Mini (right side of my desk) and using a 0,2m USB cable to connect the two, or placing the RME ADI-2 on the far left side of my desk and using a 1,0m to 1,5m USB cable to connect it.

Stacking on top of my Mac Mini will allow a shorter USB cable to be used, also it would be a convenient place for accessing and adjusting the RME, but I'm not sure about potential interference from the Mac Mini, if any at all.

Placing it at the far left side of my desk gets it away from the Mac Mini but with a longer USB run. It will also be more inconvenient to adjust it or view the display from that position, but as I'm going to be mostly using the remote for volume control, not a massive issue.

Any major issues in simply stacking it right on top of the Mac Mini and going with the shortest possible USB run?

Thank you all for your input.

 

[shadow244]

I don't know the answer for sure, although I doubt that the interference would have much affect on the digital signal.
I would just do a test with the 1-1.5m USB cable and see if you hear any difference simply picking up the dac and putting on top of the Mac or moving it off to the side.
For sure the difference between 0.2 and 1.5 mm USB cable wouldn't make any difference other than aesthetics.

 

[HarmonicTHD]

Place it wherever is most convenient. Don’t worry about the rest.

 

[unpluggged]

Why do you think a compliant USB cable of any length allowed by the standard would underperform? I would be much worried that both these devices generate considerable amounts of heat, so I'd definitely would not stack them together, unless there is constant flow of cool air around them.

Besides, ADI-2 DAC's front panel layout makes it much more convenient to operate when it's on the left, so the headphone out does not interfere with volume control and the volume control does not interfere with display.

 

[Chrispy]

Why is such a distance for the usb cable a concern in your case?

 

[Holmz]

If you do a capture of A—>D without anything playing, then you might find one spot has lower spurs coming in… like from magnetic fields coupling in.
Other than that, just put it where ever.

As a side note; the internet gets data from the other side of the world, so I do not usually worry about the last 5 feet in that context.

 

[pusillum_furem]

Why is such a distance for the usb cable a concern in your case?

Shorter runs whenever possible is best practice, even with USB. That was tested and confirmed here at ASR: https://www.audiosciencereview.com/...s/do-usb-audio-cables-make-a-difference.1887/

For me the question remains whether a 0,2m USB run with the DAC stacked on top of a Mac Mini would be preferable to a 1,5m USB run where the DAC is more isolated.

 

[staticV3]

That was tested and confirmed here at ASR:

The device used in that test does not represent the average DAC. It's highly sensitive to power and USB, as pointed out in the review:


The vast majority of DACs, including your RME, does not care about USB cable length below about 4m.

 

[pusillum_furem]

The vast majority of DACs, including your RME, does not care about USB cable length below about 4m.

OK, so what changes over the 4m mark?

 

[pusillum_furem]

As a side note; the internet gets data from the other side of the world, so I do not usually worry about the last 5 feet in that context.

A good rule of thumb to be sure, but my FLAC collection is very much local.

 

[staticV3]

OK, so what changes over the 4m mark?

There's nothing that changes specifically at the 4m mark. It's a gradient, not a binary thing.
Resistance, noise, and interference all increase with cable length.
Official guidelines limit the length of passive USB 2.0 cables to 5m while 3m is an often quoted length at which signal quality takes a downturn.
3.1 and 3.2 signals need even shorter cables if passive.

 

[pusillum_furem]

I would be much worried that both these devices generate considerable amounts of heat, so I'd definitely would not stack them together, unless there is constant flow of cool air around them.

This is a fair point. My RME is new so I don't know how much heat it can potentially generate. My Mac Mini is an i7 with 32gb RAM and the fan never turns on unless I'm executing a lengthy multi-threading task, which is not very often. However, the case does radiate some warmth, even when sitting idle.

Besides, ADI-2 DAC's front panel layout makes it much more convenient to operate when it's on the left, so the headphone out does not interfere with volume control and the volume control does not interfere with display.

Again fair point given that your signature says you own one so you're experienced in this department. Are you left handed? Seems more awkward to me to reach across the length of my desk with my right hand and fiddle with the controls than to comfortably reach up and slightly to my right, but that's only my initial impression, which could certainly change after actually running it for a few weeks.

 

[pusillum_furem]

Resistance, noise, and interference all increase with cable length.

Right, which is why I was mulling over the shorter cable but stacked DAC vs longer cable but more isolated DAC quandary.

So you are essentially saying resistance, noise, and interference all increase with length, but not to a significant level which will degrade performance on a compliant 2.0 A-B cable <3m, correct?

So in essence: a 1,5m cable will have more resistance, noise, and interference than a 0,2m cable, but because USB standardisation has dictated that those levels are acceptable for reliable data transmission until the length reaches 3,0m metres, at which point the standards dictate the transmission can no longer be deemed reliable, we simply shouldn't worry about these issues unless our USB A-B run is >3m?

 

[Berwhale]

we simply shouldn't worry about these issues unless our USB A-B run is >3m?

Yes. If you have a problem with a shorter cable, it's probably faulty. Generally speaking, the cables that come with devices like DACs are perfectly fine. It's often very cheap (i.e. poorly made) or gimmicky (coloured cable jackets, multi-angle plugs, etc.) or very expensive (i.e. audio woo) aftermarket cables that cause issues.

 

[staticV3]

From what I understand, the USB org deems >5m to be the limit at which 2.0 data can no longer be reliably delivered between in-spec USB devices, using simple copper cables.
If the USB device is poorly designed, like the Modi 2 in that test you linked, then you may see differences in performance even with cables well below 5m in length.

 

[Zek]

Maybe something like this will help ...

https://www.aliexpress.com/item/1005001997500066.html?spm=a2g0o.productlist.main.21.21f03RT13RT18w&algo_pvid=28e57711-8f97-470d-8ac4-c3d0753446e9&algo_exp_id=28e57711-8f97-470d-8ac4-c3d0753446e9-10&pdp_ext_f=%7B%22sku_id%22%3A%2212000018358971492%22%7D&pdp_npi=3%40dis%21EUR%2135.31%2135.31%21%21%21%21%21%400b0a558a16761124594047470d06a6%2112000018358971492%21sea%21SRB%21906297164&curPageLogUid=jKfMsXd2VfCh

 

[unpluggged]

Are you left handed? Seems more awkward to me to reach across the length of my desk with my right hand and fiddle with the controls than to comfortably reach up and slightly to my right, but that's only my initial impression, which could certainly change after actually running it for a few weeks.

No, I'm right-handed, and previously I had my desktop audio devices placed strictly on my right. But using RME is really much more ergonomic for me when it's on the left, even if I have to use my left hand.

Regarding the USB cables, it really should not be a problem. Any decent USB cable will work perfectly, even a very cheap one. RME themselves recommend Lindy cables, for instance. Moreover, my unit is connected to the USB hub built into my display, which is in turn connected via USB-C to my laptop, transferring DisplayPort signals, USB data, and power to the laptop. And I have absolutely no problems.