Try to find where the problem is coming from..
First of all, the guitar you are using,, does it sound good with anything else ? Rule out the guitar then..
Do the monitors sound fine with normal music etc. ?
Etc.
Keep going down the list of things to test till you find the cause of your problem.
Hopefully you will be a happy Kamper soon enough 
Cheers
When you listen at home and with the band through the PA what is the physical connector you are using to go to the studio monitors and the PA?
You our can plug the headphones straight to the headphone jack on the front of the KPA. If things sound good there then there is probably something in your output settings that need adjusting.
there are separate EQs for each output on the output menu, but starting with a known good profile is key.
are you using a factory profile? If so, which one.
sounds like you know about having the cabinet turned on since you've already swapped some of those out.
you can monitor with your IEMs from the headphone jack as well but it's probably good to get you up and sounding good before we get ahead of ourselves with aux inputs, etc.
Make sure nothing is locked before loading the profile and check eq settings in the output block
Here is what I do to thicken up or add depth to a profile. In my opinion though I believe some profiles tend to sound "fuller" "thicker" "3-D'ish" due to the miking distance when the amp was profiled. I remember reading somewhere that one of the commercial vendors here (I believe Armin/Soundside) talking about microphone placement when profiling and the impact on how this affects the depth/fullness of the captured sound. I could be entirely wrong on this since I am in no ways experienced profiling amps but I do remember reading this somewhere.
Here are some things I do that have definitely helped IMO to add depth to some profiles I use. I will usually do them in this order and tweak as I go.
1) Add a Graphic EQ in "X" slot. Boost volume in Graphic EQ somewhere around + 2
2) In the Graphic EQ I'll boost the 160hz and 320hz anywhere from 1.5 db - 3.5 db
3) Add a Compressor pedal in Stomp A - I will use this for clean and crunch/breakup tones. I normally don't use a compressor pedal for high gain tones though. Usually I set the Intensity to the 4-6 range and Attack 3-5 range.
4) In the Amp Tone Stack Section- I definitely adjust the Power Sagging after I play a open power chord until I hear the sound beginning to get "thicker" for lack of better word. Not sure why this works because I understand power sag is just how hard the tubes are working/breathing but I find it has a definite relation to the fullness of the sound.
5) In the Amp Tone Section- I will generally adjust the compressor in this (Tone Stack section) the same as I adjust the Power Sag by playing an open power chord and then just raising the level until I hear it adding to the depth of the sound. Once I hear the sound becoming fuller I stop. More is not always better and can make things muddy and lose character. I'm careful with this though the more gain I am using since I tend to like this parameter adjusted higher more on the clean and edge breakup profiles.
6) Add the Pure Boost pedal in slot B or C and increase the volume slightly in the Pure Boost parameter
7) Reverb! - Reverb applied correctly IMO will really help shape the depth of the sound. I usually set my reverb time at 2.5 , predelay at 100ms mix around 25%-50% (depending on profile) damping at 5 bandwidth at 3.5 and freq at -1.5. I got these settings off someone here at the forum and have been using this for my reverb for a while now.
A couple of other things I'll do if I still feel it sounds a bit thin.
1) Add ANOTHER Graphic EQ in Stomp D .....boost some lows and mid ....boost volume in EQ pedal
2) Add Stereo Widener in Mod Stomp - Set Intensity to around 4 Tune around 5
Like I said some of this may not be the "correct" way but it works for me. I struggled like you with a lot of profiles I tried in the beginning sounding way too thin. I've now spent many many hours trying to figure this out and have come up with the above to help make my profiles sound bigger. I'm open to anyone else's suggestions as well because I'm always looking to get better.
Keep in mind too some profiles I believe (IMO) are mic'd better than other profiles and thus sound better. If you do the above steps and its not working for you ditch that profile for another. Starting with a profile that sounds super thin to begin with is not ideal keep looking until you find one that is in at least range of working with.
Anyone out there confirm (from profiling experience) that placing the mic further from the amp when profiling would capture a bigger/thicker/fuller sound? Not sure if it would but remember someone talking about it on here.
For a disco clean sound there is a free Kemper profile in one of the rig packs which is for the song Get Lucky by Daft Punk featuring Nile Rodgers I use this live for a few disco type songs and it fits very well search the Rig Exchange for "Get Lucky" I'm sure it will be on there
No(t) luck(y) for me 
...any hint? X)
IMHO before you tweak your ass off.
1) Make 100% sure your connections are correct
2) Reset global values (under settings on kemper)
3) Just find a profile that sounds good and tweak it to ur liking if needed. If the profile is good and suits ur guitar it should sound great from the get go. In rarely tweak and when I do it's mostly a tiny eq adjustment.
I would like to add that if I get a FRFR cab, it will be for home use and not stage. I run direct to p.a. and use in ear monitors live.
For home use at relatively low volume, I'd look at studio monitors,a FRFRFR cab will always need higher volume to deliver the tone, just because the speaker is bigger. Do a search here and you will find what people recommend. I have a pair of Equators and they sound fantastic. Again, I don't know how my guitar sounds dry because I never play at such low volumes
a FRFRFR cab will always need higher volume to deliver the tone, just because the speaker is bigger.
I'd not agree with that in general.
I have no experience with 12" linear cabs used at home volume, but the CLR sound very good at 3 a.m.
All the difference I perceive when changing volume with them is just FM effect.
There is a point to make tho, and it's related to the monitor's specs.
Here follow a quotation from my next essay "JM: The Man, the Myth, the Facts" .D
QuoteDisplay MoreQ: The spec-sheets of many significantly smaller (studio) monitors, with 6-8" woofers, claim them to go down to as low as 40Hz or so, even within a +/- 3db interval. Now in real world performance, will these monitors, despite being comparatively tiny, indeed provide an extended bass range compared to CLRs? Is that even physically possible?
A: At the much lower listening levels for which small monitors are designed, yes. The significance of the additional bandwidth - slightly less than an octave - at such low levels varies substantially with program material, the hearing acuity of the listener(s), and the low-frequency support provided by the acoustic environment.
Q: Does this mean that the CLRs will provide a more limited bass response compared to a set of studio monitors that are rated to go down to about 45-50Hz even when run at the same low listening level?
A: Depends on the accuracy of the rating of the monitor in question. That varies widely.
So, basically, if a studio monitor has actually got better specs in terms of frequency extension (that is, if the datasheet is true), if the listener is able to properly hear very low frequencies and if the room fits, its response on the lows will be deeper. This will not be related to playback volume tho, but to the design in itself.
Of course, when it comes to only playing guitar, this deeper low end is less meaningful.
For home use at relatively low volume, I'd look at studio monitors,a FRFRFR cab will always need higher volume to deliver the tone, just because the speaker is bigger. Do a search here and you will find what people recommend. I have a pair of Equators and they sound fantastic. Again, I don't know how my guitar sounds dry because I never play at such low volumes
Display MoreI'd not agree with that in general.
I have no experience with 12" linear cabs used at home volume, but the CLR sound very good at 3 a.m.
All the difference I perceive when changing volume with them is just FM effect.
There is a point to make tho, and it's related to the monitor's specs.
Here follow a quotation from my next essay "JM: The Man, the Myth, the Facts"
So, basically, if a studio monitor has actually got better specs in terms of frequency extension (that is, if the datasheet is true), if the listener is able to properly hear very low frequencies and if the room fits, its response on the lows will be deeper. This will not be related to playback volume tho, but to the design in itself.
Of course, when it comes to only playing guitar, this deeper low end is less meaningful.
Anyone else care to chime in on this? I've been curious about this regarding FRFR cabs. I only play at home and have a Friedman ASM-12 wedge. It seems to sound best and in its sweet spot cranked up which is not ideal for home playing most of the time. Not sure if this is the phenomena of how we perceive sound and louder just seems better or if the cab really needs to be pushed to reach it's intended full potential?
Anyone else care to chime in on this? I've been curious about this regarding FRFR cabs. I only play at home and have a Friedman ASM-12 wedge. It seems to sound best and in its sweet spot cranked up which is not ideal for home playing most of the time. Not sure if this is the phenomena of how we perceive sound and louder just seems better or if the cab really needs to be pushed to reach it's intended full potential?
Here is my take. The Fletcher Munson curve tells us that the louder the sound source, the more pronounced the lows and highs will be. I agree with you that my FRFR (DXR10) sounds much better when playing at volumes that are simply unsuitable for apartment living. I don't think it's necessarily about driving or pushing the cabinet or speakers, but I won't discount that as a contributing factor.
Guys, if a linear cab's response is function of its volume, then the cab is not linear. And provided one happens to use such a cab, and needs to have it distort in order to sound better, then they might as well use a FR cab, which is just designed in order to not be linear and please guitarists
On a more serious note, when it comes to a loud sound we should take into account two more factors:
These two factors are clearly not (directly) related to how much non-linear the cab is.
