System Plateau - Ideas?

Do you still have your LM tube amp lying around by chance?

What do you mean by missing "edge", does that mean you are missing more detail or snap or resolution somehow...

Also, noticed you went from nice tube to nice solid state amplification, and while both are nice - they are different in sound and presentation as you well know having owned both of these very nice amplifiers.

Past few years I hit that spot again myself. Went back to rotating in SS vs. Tube amps again, and landed back at tube amps for one simple reason - the ability to make changes on the fly. Re-trying a wide variety of different input/driver tubes allowing for quick change of sound. While the J2 amp is super nice, you’re kinda locked in, it is what it is, and maybe some IC cable swaps to mess with tone a bit. Cable changes can be fun with SS amps too, a whole topic in itself of course. With your LM amp or other tube amps, you can try and rotate in different caps and different tubes to keep it interesting versus having to buy new speakers or other expensive components.

Some spend decades simply rotating tubes and coupling caps in tube preamps and tube amps for different flavors of sound. With your J2 it’s not like you are going to pop in different JFETs or different transformers, pretty much have to go with what Nelson picked, which also makes that a great amplifier - catch22. :) Don’t let go of that J2 though, keep it if you can. Always fun to rotate a nice ss amp back in too. Different flavors of ice cream! Just wanted to share you are not alone, many of us do the same... kinda what audiophiles do perhaps. Have fun.  :) 

@dotchaos
@decooney I won't let go of the FirstWatt, also won't let go of the Line Magnetic (at least until I can afford the 845 premium). I did take the LM as far as I could with tube selection, but didn't get to playing around with caps at all.

With a push from a few local mentors who've been doing this for 60+ years, they led me down a path that started with tube rolling and ended with high-end coupling caps on my last three tube amp setups, fwiw.  

@dotchaos
"edge". That wasn’t the right word at all. I think what I’m missing is the fullness/roundness of the Line Magnetic. The slightly "thinner" sound of the current set up leaves me wanting a bit.

@audition__audio do you have a preferred brand you’d recommend, for cables? I’m using ICs from an Etsy outfit called Amplifier Surgery, Blue Jean speaker cables. All very low-budget. Forgot to mention that I’ve been looking to upgrade the turntable, as well. Haven’t seen a clear next choice, there (many options).

@dotchao
Looking back over a few of your comments and others. A few touched on this already, and I’ll add a few comments in support of this angle.

Yes, "cables" and and interconnects specifically may very well be one area to re-focus on as a next step with the "current (J2) setup" as you referred to in your last update. Yes, your LM518ia with 845s in Triode mode will have a lush and more rounded off sound with more fullness. You can tone-tune the J2 setup a bit with different ICs, for sure.

To save $ and prevent costly do-overs, you could reach out to TheCableCo and take advantage of their cable Loaner Program. Or, find a helpful local dealer who’ll let you take home 3-4 pairs of different "well used" interconnects to try for a few weeks. Ask for warm IC cables...

FYI, I’ve re-sold multiple pairs of older legacy high end Cardas ICs to Nelson amp owners trying to smooth out or fill-out the sound a bit more due to the leanness you referred to in your current setup. Root cause can be speakers/matching, but you can cheat some by trying and rolling some different interconnects with your J2 (IF) you plan to stay with your current SS amp and speakers. Will say an 845/Triode amp is pretty unique and hard to duplicate compared to most SS amps, yet the J2 is the one I'd pick if I were doing lower power FirstWatt SS.  Good luck.