Osiris

It does that - pushed valve amp, just fattening up the sound without obviously distorting it - sound brilliantly. From what I've heard of the MK3 it's more of a modern distortion sound, but the MK2 is definitely more on the vintage side.

Mildred, my love... Oops sorry, just having a flash back 😲 I can't speak for the EBS Microbass 3 but I've been using its predecessor, the Microbass 2 for some time now and it fills your requirements perfectly. It's not obvious from looking at it but you can link the 2 channels to give you a very flexible EQ section with parametric mids, a mid cut/treble boost sweep on the treble control using the filter button, and a broad bell shaped treble boost (preferable to shelving types, IMO) using the Edge control. The gain control on the drive channel goes from clean through some authentic sounding edge of breakup type sounds and beyond. There's also a little valve (or toob* as the cool kids call it these days) simulation button that adds a fatness to the signal without overdriving it. I've not tried it myself but I'm assuming you could use the fx loop return as an aux input too. I don't think it's in production now that the mk3 is out but you can pick up used ones fairly cheaply. *Not to be confused with a certain Manc halfwit.

There's a very favourable review of it linked below. It also has transformer driven outputs which I suspect may make @krispn uncomfortably moist 😀 https://www.compressorpedalreviews.com/post/warm-audio-pedal76-compressor-review

I also replaced the pickup in my Lionel, not that there was anything wrong with the stock pickup and I really like the staggered pole piece arrangement of it too. But as has been said, it's a very modern and clean sounding pickup, not bad characteristics in themselves but it lacks that warmth and low mid thump of the classic Precision sound which is what I was expecting from a bass with a pickup like this. So it might look like a P but it doesn't sound like one. Like the lovely @Adee I swapped mine out for an EMG Geezer Butler and it now sounds more like I want it to, although compared to my JMJ Mustang the pickup in the Lionel is around 10-15mm closer to the bridge so it has a slightly different inherent tone due to its position. The JMJ sounds much more Precision-like whereas the Lionel has its own voice, a bit of the P flavour but not full fat.

Just received another loom from John to replace the guts in my cheap and cheerful Harley Benton. Quick and easy to install even for a kack-handed idiot like me, and sounds great with a smooth even taper. Great price, great comms and a quick turn around too. Cheers John!

Hope this helps. FWIW, I've tried to match the string spacing on my Lionel (still a daft name for an awesome bass!) to match the JMJ, and while it's close the Sandberg strings are a fraction of a mm wider even at the closest even spacing than the JMJ.

I don't know the numbers off the top of my head but I've played several different Mustang variants, including owning a Mexican PJ as well as a JMJ, and the spacing varies. The PJ, Squires and IIRC the current top of the line Performer (which was also the most underwhelming IMO) all have tighter spacing and slimmer necks than the JMJ, they're more jazz like necks with narrower nuts. The JMJ is a more chunky P like neck with wider spacing, but still comfortable and addictive to play. The JMJ models definitely live up to the hype and I regularly gig mine in preference to my Sandberg shorty.

I get that, there's always that feeling that there's something out there that's better even if what you already have sounds great and does everything you need it to. I've been using the Boss LMB-3 for 20 years or so on and off and keep trying more expensive units on the assumption that they'll be somehow better. But despite having tried some cracking units that are great in their own way, there's something about the way the Boss adds an addictive aggressive punch to the mids that I've not been able to get from any other unit. The DG Hyper Luminal was close and the Basswitch dual band even closer, but the cheap old Boss does everything I need. Agreed, it's an excellent unit in its own right and lives up to the hype it gets but I found it didn't play too well with my EBS preamp, and as most of my gigs are on IEM's these days, having the right preamp is more important for me. And yet I'm still curious to try the updated model. 🤷‍♂️

I wouldn't have thought that a Cali76, or any other 1176 based unit, would be the most appropriate choice for fretless as the 1176 and its offspring are FET based designs which are very fast and impart colour on the signal which I'd guess is not overly desirable for clean fretless playing. However, I'm not a fretless player but optical units, like your Ampeg Opto comp, are slower and generally warmer sounding. But as with anything, it's down to personal preference and whatever works for you. I'm half tempted by the new Cali76 as I like FET based comps as they work well with my heavy handed technique - a legacy from when I started playing 40 odd years ago as an angry young teenager, but like @peteb commented above, I struggle to justify dropping £300 on a single pedal, no matter how good it is. But that's not to say I won't at some point...

Treat yourself to an Orange Squeezer if you can find one, I think they haven't been made since the 70's. No controls at all other than an on/off switch 😁

Apologies, I misunderstood your original post. It takes time to get your ear in although it's really more of a feel thing, the way the bass is more consistent and present in the mix, if that makes sense? I don't have anything particularly helpful to add in answer to this other than keep experimenting to see what works best in he different contexts.

From what you've said here, I think your thoughts about the hardware you're using are irrelevant. By your own admission you don't understand compression so in that case it doesn't really matter what model of compressor you're using if you don't know how to get the best out of it. My stock response to questions like this - and they crop up frequently - is to spend some time doing your homework. Read up on what each parameter does and how they interact then start to apply that knowledge to setting the compressor up to do what you want it to. You're get more helpful information from sound engineering sites than places like here and Reddit 😉 And the best way to do this is at volume with the band, assuming you play in one, as you'll then start to better hear and feel the consistency that the compressor is giving to your sound. It will take time and a lot of experimentation, but once you get it right, you'll never want to switch it off. And don't think of compression as an effect, think of it in the same way as EQ and HPF. I think a lot of people have problems with compressors as they assume they're going to be an obvious effect like a drive or synth, they're not, they are more subtle than that but infinitely more useful, IMO. This is not meant to sound condescending in any way, it's just a lot of the anti-compression arguments come from a lack of understanding of the principles of compression and how to apply it.

Are you looking for something narrow front to back or width ways? If you're for something narrow front to back try searching online for 'shallow rack'. I think Thomann sell some half width rack cases if that's what you're after.

Joyo Pipebomb? The Joyo Iron man series of pedals are ridiculously tiny.

That's actually quite common for some compressors, it's the same thing that the strangely alluring @Frank Blank describes in his post preceding yours. They add a certain something to your tone that isn't compression as such but still enhances your tone. But not all of them do it, the 1176 rack unit and the Origin Cali76 are probably the most famous examples of ones that add something, as is the Diamond. And on the other side you have things like the Aguilar TLC which are ultra-transparent and neither add nor take away from your tone. Personally, I prefer something that adds its own character, and as you have observed, it's something you can't really recrate any other way.