The only issue I see here, a minor one, is the input jack on the wrong side, like the old Fuzz Faces.
Odd choice for a modern pedal designed for a modern pedalboard. But the value is incredible for the price.
Had an interesting discussion with Tom Bowlus about this topic. Sharing it below for educational purposes:
In our opinion, it comes from early guitar amps (mostly UK) having the inputs on the right and a right to left signal path. Our supposition is consistent with their driving on the left and their drivers seat being on the right (mirror image to us). Marshall is probably the best example of this with the earlier JTM series like the JTM-45. Being that they got stuck in their own legacy, this continues today.
Even with Mesa, we started out with the input on the right and a right to left signal path, but when Dan started designing the bass products we switched to the input on the left and a left to right signal path. This is what MOST bass amps follow, it's what I have used my entire career, and it's probably because there's a tighter link between the bass market and the pro audio market than with the guitar market which kind of does its own thing (warts and all).
The obvious difference is Fender, which has always followed the American style of input on the left and left to right signal flow.
A quirk with Mesa is that some of our guitar products are one way and some are the other way... and in some cases in high gain amps, the crosstalk was much better one way versus the other. In high gain amps, excessive crosstalk can cause ocillations which are a very issue.
Dang. It’s the Nordy Starlifter all over again.
There are others who follow this left to right path too, mostly higher end preamps like Berganitno, Nordstrom’s, Grace, ISP, Benson, and of course Genzler. If the signal flow is right to left, then it makes sense to have the jacks the other way.
the proud phrase
"Made In Petaluma, CA, USA With The World's Finest Materials" 
on the back is no more ...... not saying it's not a quality product, (i have not test driven it yet) I'm sure it's a good product and good decision for the parent Co.
I wonder if the proud phrase will start disappearing across the board.
No, it may only come up for occasional products that simply can’t be manufactured here at a cost that players are willing (or able) to pay. This represents an infinitesimally small part of our business. In this case one pedal out of an entire bass amp and speaker line.
Wondering if the Mesa will have a noticeable tone difference compared to the Genzler Magellan preamp, (which I have).
Completely different.
Andy posted it is a complete different design than Genzler
It's all Mesa and All Andy
Correct, there is no mistaking the two preamps.
Question for @agedhorse :
Does the aux input pass a stereo signal to the headphone output, or does it sum to mono.
It sums the signal to mono and it remains mono through the headphone output.
As a Genzler Magellan preamp user, I see it as quite transparent, so I'm guessing the Mesa will have more of a 'baked in' tone. Nice to have a quality alternative to the Genzler.
Correct, both are “best of their respective worlds”. (IMO)