Please listen... is this the way Kemper should sound?? Problem with sound

at least you're willing to fix stuff your end, a lot of people would have given up by now.

Quote from MarkusUz

True, but a categorical difference is not due to a week older set of strings. Only nuances.
Trying to solve this problem I have went through Elixir, Ernie Balls, NYXL and finally now DR DDT. And different gauges. None of them removed the problem, whether they were brand new or they had been there for months.

Strings, age of strings, fingers, pick, pickups... yes, all of them have an effect. But I feel that categorically they are just bringing flavor. They don't mean anything if the gear doesn't work properly. There's no way to play or EQ your way out of a deficient piece of gear.

My guitar is deficient, the strings just don't ring and the wood just doesn't resonate as it should. I have no way to explain it to myself how it has taken me years to reach this conclusion! I feel utterly embarrassed. I have blamed Kemper, tweaked kemper, changed strings, changed pickups, changed to SPDIF, reinforced my floyd rose springs, dampened the springs, dampened the strings beyond nut, sorted intonation, I have brought it to storekeepers for a listen... and all this time the answer has been sitting on my lap! But as I have said, I have learned a lot about sound.

Hah!! No need to feel embarrased. I think everybody's been there.

Although you can't change the resonance of the guitar unplugged, you MAY be able to make up for it by playing with the pickup heights, maybe to a degree where you're satisfied with it. Who knows, when you find the sweet spot, you might actually like it better? Adjusting pickup heights is definitely a worthwhile endavour. the absolute worst case is that you'll only learn something

When you get them close, try using an EQ stomp before the stack and see if you can make some minor adjustments there and get even closer. Or maybe try putting the "regular" EQ (in the stack) in PRE position rather than post.

If the guitars sound different unplugged, it may be because they have different Floyd Rose tremolos on them - some are all steel, some pot metal, etc.

One quick fix - change the pickups. Your brother's guitar has Duncan Pickups, and your guitar has EMGs? in my opinion, EMGs are not a good match for many guitars.

emg's are typically recommended to raise the pickup height to be much closer to the strings than passives. They also get weird if your battery gets low, and ive heard they sound better if you use 2 9v batteries in series to get 18v.

Low action plays great but doesn't sound as full and dynamic for me. Raise the action a little on yours and see what happens.

Of course this depends on your fingers

Quote from MarkusUz

I measured from after the first transient to before the next transient. I put it on a loop to see what volume it shows. They were equal down to 0.0 dB. But the transients are louder in JJ, definitely. But to me the only important thing here is that I have been struggling with that faint and cloudy guitar sound for months and months, and since JJ doesn't have it, I know now for sure that it's my guitar. And for the following reason, it doesn't really matter if they are equal in those samples...
Yesterday I compared the guitars with just strumming them without any gear involved... and the difference is clear. Plain and simple, it's the guitar itself, not pickups or anything. It's disturbingly odd because they are basically the same guitar. Exact same shape, color, floyd rose, price was categorically the same (if I remember correctly). Only he had one more SD pick up in the middle, and as I said, I changed my SDs to EMG actives (along with tone pot), and he has a 5-way switch, mine has 3, he also has some other little switch there, but I'm not sure if it's working properly.

Almost identical guitar, and even just playing it acoustically there's a big difference. The "JJ" is much punchier and brighter, almost like something in the "MM" is dampening the strings. The floyd roses should at least be the same, so then it would leave nothing else but the wood body itself. I can't come to any other conclusion.

Mentals point about strings is very valid. You get a much brighter, punchier sound from a guitar when you put on new strings if the the old ones have been on for a while.