AC or DC output, it's still a wall wart. As my example in the $399 Cambridge Audio MXN-10, the power supply is internal and quite compact (See below). It wouldn't take a whole lot of engineering to put something similar in the JDS unit.
It's rated at a 5V/4A output.
Look, Cogito we know you don't want this. You don't see a use case. You prefer other solutions. You've been clear on that.
You probably shouldn't give it another thought.
However with all of the performance, function, well thought out capabilities that are evident in the Element IV (whether they suit your needs or not), I think we can all see it's not lack of engineering that resulted in the use of a wall wart.
To suggest "it wouldn't take a whole lot of engineering" to put the transformer in the case is missing the point.
But it would take a WHOLE LOT of engineering to fit it into THAT case!
Why ruin the product with bulk that can be stuck under the desk?
It's a great form factor: A big, luxurious volume knob! With enough 'base' to support it, but not take away from the space-volume above my desktop. And functionality that customers have requested!
Engineering is beyond 'fitting it in', even at a price point. Among so many other things, engineering considers the end use and the customer's preferences.
I believe JDS Labs developed this in response to vocal customers, who peppered JDS with requests for these features (based on what I 've seen on his blog anyway).
I think it's a great performance result, and a great value. Not for everyone? Okay, what is?
Anyway, there are some good reasons to keep the transformer (or SMPS) separate.
1) Desktop space. Personally, I don't want the extra bulk on my desktop, when my PC, my multiple monitors, my dock, etc. already have floor-bricks.
2) Form factor. Keeping things small is more difficult with large internal components. Plenty of space in the MXN-10, sure. I don't want to keep it on my desk.
3) Internal EMC. Particularly with SMPS (not in this Element, but in general), but also avoiding near-field E/H problems.
4) Regulatory EMC.
5) Regulatory Safety - bringing line power into the case can alter many things about PCB design and product insulation. There is an advantage to using a Class 2 power supply.
6) Component supply chain issues - much simpler when adapting to line voltages in other countries, but also in adapting to supply & demand issues in the component market.
There are others, but to me personally, the big one is the desktop space.
I agree, it sounds attractive to power from USB-C PD, but that certainly seems like it could introduce SMPS noise, which may be detrimental to the path (or require additional filtering/noise suppression), not to mention raising the cost.
By the way, although the MXN-10 in your example uses a 5V/4A supply module, the JDS Labs Element IV can supply 3.2W into 32 Ohms, which requires higher voltage swing to achieve. The MXN-10 output is 2Vrms, correct? Does it have a headphone output? How much power can it drive into 32 Ohms?
