Once again, with strings-- given different basses, hands, and preferences,
YMMV. What follows, relates to
my experience and
my preferences. How well anyone's generalizes is not clear. Before going further, I will say that I suspect that you're over-thinking all of this. My view these days is that all strings demand compromise in one area or another. Find a set that works for the most part and then go and play. Your playing style will adapt to the strings to some extent. If you're looking for a set of strings, including mixes, that you will find to be "just right" all of the time, then you will end up spending a ton of $$$ and being frustrated.
...
I've been struggling with the thinness of the G string, which also translates to boominess in the low end of my bass. I've tried lots of different EQ methods balance the top and bottom end tone. I usually still end up with the G string just being too thin. Sometimes I've had success using a high pass filter on my signal, or combining the pickup with a mic, but the more variables you introduce, the more you multiply your headaches.
I've always found Spiro weichs to be a bit too weak for my tastes. That has much to do with my playing style. My bass wears Spiro mitts. There is no high-pass filter on my bass. Nor are there any tone controls. Really, I looked. Okay, I'm being facetious.

My point is that I think you're wise to try and get the acoustic sound right and not try to solve perceived problems with electronics (realizing the practical reality that you are playing amplified).
...I had a gig that night, and was able to test them out with a group. I immediately flashed back a couple of years to when I used Obligatos for about 3 months.
With the Obligatos, the seem loud and warm at first. However, playing jazz both soloing and walking, I eventually decided they don't have the same kind of headroom as Spirocores. By that I mean when they seem to speak and maintain their town and medium and medium loud volumes, but when you really dig in, they kind of top out and the tone actually thins out some.
I've posted about this here at least 10 times over the years. Oblis sound great in the living room but they give up on the bandstand. You dig in, they give up. Whether or not this is an issue depends on one's playing style. The fact that you had this experience seems to provide important information about your playing style and preferences.
The overall tone of the Evahs seem to be warmer, and much more interesting and colorful. I can definitely hear more overtones in the Evahs even though I would describe the overall tone to be less bright than the Spirocores. And while they do have kind of a nice attack, the tone seems slightly more transparent than the Spirocores.
The spirocores are less interesting sounding, but seem to have a little more impact, which might be what translates into boominess in the low E and A.
Our experiences sure differ here. No other string I've played ever had more impact than the Evah mediums or weichs. I've found Spiros to have the more rich overtone profile as compared to Evahs. Your description is confusing as you say you hear more overtones with the Evahs but that the Spiros are brighter. Usually, more overtones translates to brighter.
Second, I'm going to let them break in, but I will probably at some point order Evah solo E and A. However, I'm wondering if anyone has tried the solos at concert pitch and also their Weichs and how they compare growl and sustain wise. From what I've been reading the Weichs have gotten favorable comments about the growl and sustain, but I haven't seem many comments about that when it comes to the solos.
And eventually I'll probably end up trying a set of Evah Weichs, but I'm really enjoying the nice feel of the solos at concert pitch. Are the Weichs very much stiffer?
Solos, weichs, mixed sets, etc. Really, I think you'll drive yourself crazy. You're heading right down the dreaded string vortex. I'm trying to help. Reading everything you wrote, it seems that you're not happy with a set of Spiro weichs (thin top end, boomy low end). You do seem to like the Evahs. Here's my advice. Get a full set of Evah weichs. Put them on your bass. Play them for a few months. This will allow the strings, the bass, your hands, and your ears to all settle and get to know each other.
Or, you can continue down your current path and then I can suggest a few good therapists in your area.
