Yes, that is exactly what I am suggesting. We like to think there are huge subjective differences, but unfortunately the science rarely agrees and that can be hard for our egos to deal with. Jon said this really well once.
When you get into the world of studio preamps, people have their preferences and biases and experiences, but almost none can express those in technical terms, and when their subjective evaluations get challenged with actual technical measurements, suddenly they get very very defensive . . .
Preamps have a simple, defined purpose; Amplify a low-level signal equally across all frequencies while introducing as little noise as possible. There might be some secondary functions like bass roll-off, but otherwise it should be ruler flat 20 Hz to 20 kHz. Unfortunately, a mountain of bad science and marketing bullshit in the audio world has obscured this very simple purpose and led people to believe that a preamp should be 'bright' or 'dark' or... whatever.
If you really think you understand the sonic characteristics of these preamps, then I would challenge you to discuss them in technical terms rather than anecdotes. A frequency response chart or Bode plot is not hard to generate, even the most humble of computer sound cards can take accurate measurements. If you really think these two preamps share a sonic characteristic, then surely we would see evidence of that in a frequency response chart, right? How about looking at THD and harmonics? Shouldn't those also match? I've taken measurements on all these pres and would encourage anyone to do the same. It's not hard; everyone should know how to do it.
Heck, even some sound comps would be better than anecdotes. As maybe the only person on this forum with a 4Minx, why haven't you done this?
What's so hard to believe about AETA basing the pres from their OWN wonderful sounding PSP-3? Why change a great pre?
Because that's not how engineering works. You don't start with a sound and work backwards. You don't make 20 different circuits and perform critical listening tests until you find the circuit that "has that classic Aeta sound." Engineers work with a set of technical requirements (i.e. ruler flat frequency response, low power consumption, specific gain ranges), choose parts based on component level specifications, pricing & availability, reliability, etc... and then validate everything with technical measurements,
not their ears.
And as for the second-hand knowledge you are throwing around regarding Aeta's opinion, do you really believe that an engineer at Aeta would say "the 4minx was designed to sound like the PSP-3" when they have released so many products since? Why wouldn't he have said it was based off the Mixy or the Scoop or any other product developed by Aeta that is literally lightyears ahead of the PSP-3? The answer is pretty simple. A taper asked him "does it sound more like X or Y" and he responded with the option that made the most sense. This kind of anecdotal information might be interesting, but is easily misused and often does more harm than good.
Are you suggesting transformerless pres all sound alike? And by all means, let us all know the dozen pres that sound like the PSP-3. I'd love to try them out.
If we're talking about modern, instrumentation amplifier based pres (INA217/SSM2017/THAT151x or the dozens of other, newer chips out there), then yes. It's an incredibly common circuit topology and not the secret sauce or voodoo magic you'd like it to be.
Aeta did a great job engineering the PSP-3, but I can assure you that the overwhelming majority of R&D was focused on enclosure design, pcb layout work, implementing features like M/S decoding, left/right balance, power supply design, etc. Heck, more than half the circuity in the PSP-3 is dedicated to these auxiliary features alone. The amplification circuit is probably the simplest thing in there and even then, it's fairly dated. For example, there are definitely more exotic ways tackle dc offest across the entire gain range than a 1000uF capacitor in series with Rg and with some of the newer chips, you don't even have to solve for it.
The same goes for the 4Minx, but now you've got all sorts of digital stuff in the mix, firmware coding, etc. That stuff is what makes a solid, modern product, not the 'sound.'
I can think of a few pres with wildly difference sonic signatures, but that isn't necessarily a good thing (I'm looking at you m248... worst fucking preamp ever. keep getting fleeced, sheep).
It would behoove all of use to focus on features, pricing, and customer service / support rather than "sound."