As far as we know, Kemper is not going to produce a poweramp for the non-powered head. They ran into issues with EU Certification for the design they had in mind.
Do you really need to modify the KPA when a separate 1U poweramp would do the job. You can even get 1/2-size fullrange poweramps so that you can fit it alongside a wireless-receiver and squeeze everything you need for the road in one compact 4U FX-rack.
No need with a rack, just buy yourself something like a Matrix GT1000FX and you are ready to rock!
+1 here for the matrix! Absolute superb customer service too, see my thread in 'other gear'
Some like the EHX Magnum 44 which is the size of a pedal. You could put it on your pedalboard or on a rack chelf.
I saw a really cheap one on Thomann but I'm not sure if it's just going to be junk. I was thinking it might be worth a go as I won't be using the power amp all the time. It'll be more of an extra option in case I go to a venue and have to use a guitar cab.
thomann.de/gb/harley_benton_gp…08bb8f7a4bbc7807151c3751f
Has anybody tried this thing yet?
It seems like a good deal for the price as the Velocity is nearly double the price...
I am using InEars most time, but in the rehearsal room i don´t want to be yelled at all the time if i have the plugs in my ear 
Because, to be honest, i don´t hear myself over the PA. Some Problem i didn´t have when i had my good old 4x12 screaming at me. So maybe the cheap Poweramp on top of a 4x12 could give me this well known feeling back. With a little tweaking in the Monitor EQ the sound should be ok i think.
Guitarist problems ..... 
I haven't heard anything about Harley Bentons being more than real basic, so perhaps you should consider an option that suits your investment in the Kemper.
As far as form factor, the Camplifier takes it as the best after-market power amp for the Kemper in my book.
I and many others use this: http://www.behringer.com/EN/Products/EPQ900.aspx
As far as form factor, the Camplifier takes it as the best after-market power amp for the Kemper in my book.
Yeah, but the OP owns a rack.
I'll second the EH Magnum 44 recommendation. I play gigs with my Kemper where I'll usually use both the house-monitoring as well as a provided 4x12 guitar cab. I have a 3 unit rack and actually velcro'd the Magnum in the back of the rack (behind the Kemper). Works well and I was shocked at how good it sounded for the price and how loud it can get (louder than I need and we play punk/hardcore type music). Good and cheap option if it's only for monitoring purposes.
(...) It'll be more of an extra option in case I go to a venue and have to use a guitar cab. (...)
Some like the EHX Magnum 44 which is the size of a pedal. You could put it on your pedalboard or on a rack chelf. (...)
I have tried some of Thomann´s own Products and my opinion strongly depends on what kind of product i used
For example:
I personally don´t want to spend too much money for a thing i dont really use that much.
I just need a cheap solution to get rid of the ear buds while rehearsals. It doesn´t even matter much to me if the sound is perfect in this case... i just want something that makes "loud" 
Of course it is not the perfect solution for somebody that wants a perfect sound on stage. But for somebody who needs a cheap poweramp (for the rackmount KPA) it could be a good deal IMO.
I personally never wanted to have a poweramp with my KPA as i didn´t need it in the past. But for some reasons i want to try it for rehearsals.
I have the non powered verson, but have som space in my rack for a poweramp. I realy think it would be nice to play my Kemper trough my CAE 2x12 cab!
Yeah, but the OP owns a rack.
Well-spotted, Sir! I think the OP should go for an appropriate rack-mountable solution, such as something from the house of Matrix. Just a clean, transparent power amp which doesn't distort, not too sure of the many options on the market.
Well-spotted, Sir! I think the OP should go for an appropriate rack-mountable solution, such as something from the house of Matrix. Just a clean, transparent power amp which doesn't distort, not too sure of the many options on the market.
The house of Matrix is an excellent choice!
I just boght a EHX Magnum 44 and can't wait to try it out. It's such a small little piece of gear, but I really hope it does the work it's supposed to do!
When I was considering buying one for my 2x12" I asked over TGP as well, and I got some positive responses both in terms of headroom and SPL. All makes me think it should work great.
Then I started looking for something I could retrofit the Profiler with at the same prize, much more practical to manage, to power, to carry around etc.
