Hi all and thanks for any help in advance.
I have just bought a power rack and want to know if it can be used without the amp and also can it be used with the amp and non amped outputs to PA simultaneously. And lastly if the latter can be done can you control the cab modelling independently to each output.
Thanks for your help
Ian
Welcome, Ian, and yes to all your questions.
Ciao Ian, welcome 
Quotecan you control the cab modelling independently to each output.
What you can do is to apply the same cab to both outputs, exclude cab on both, or just from the Monitor\Speaker output.
Typically you'll use your Monitor Out for using a powered monitoring system, like an active FRFR cab, or the powered out for powering a passive monitoring system, like a guitar cab. They are connected internally to the same path, and you can toggle, in the output settings, whether the "cab" block is enabled on the monitor out.
You can use that in conjunction with the Main Outs to feed the house (XLRs, 1/4"s, or both, however you cannot adjust their levels or EQ independently of one another). This will always have the cab block on, unless disabled on the profile as a whole.
If you only have one output to the PA available to you, you want to be sure to select the mono output for your main output. This makes both sets of main outputs (XLR and 1/4", which all 4 can be used at the same time actually) perform in mono mode. Keeping it in stereo and using only one side will result in missing parts of stereo effects. This primarily affects delays, but other effects can be in stereo as well, which will cause issues or inaccurate/incomplete sound. The monitor out is always mono.
If you have a stereo guitar rig, you can use the monitor out or power amp out to left (or right), and the direct out/send to the other side, by adjusting your output settings. This, however, will require a power amp on the direct out, and cannot be done if you're using an FX loop (as it uses the direct out as a send).
Finally, you might want to read up on the output section of the Reference Manual (not the one that comes with the Kemper, but just google it and it's one of the top results). If you haven't read the manual yet, it's an easy read, and will tell you everything about the Kemper. There's lot of options for adjusting how your outputs work, and many are ideal for reamping or studio use.
Regarding your first question , if you use the Power Rack and don't want to use the power section , you should still connect it to a speaker cabinet . The information I got when I asked this same question is that the Kemper Power Rack wont be damaged but having no speaker load will change the sound . The advice given to me for direct recording , where I don't need any cabinet sound is to connect a speaker cabinet and then set the power amp volume to zero.Hopefully, this is correct advice.
Welcome Ian!
I'll be using the unit for recording directly only, so I defer wisdom on using cabs to my esteemed fellow Kemperites.
The information I got when I asked this same question is that the Kemper Power Rack wont be damaged but having no speaker load will change the sound .
Paul, where does this information come from?
From one of the sales reps at Sweetwater Sound .I asked my sales rep about using the Kemper Power Rack without a load on it and he got that information from another sweetwater tech that he claims knows the products well. That's as much as I know .Maybe someone can confirm if this is the case or not .
Regarding your first question , if you use the Power Rack and don't want to use the power section , you should still connect it to a speaker cabinet . The information I got when I asked this same question is that the Kemper Power Rack wont be damaged but having no speaker load will change the sound . The advice given to me for direct recording , where I don't need any cabinet sound is to connect a speaker cabinet and then set the power amp volume to zero.Hopefully, this is correct advice.
From one of the sales reps at Sweetwater Sound .I asked my sales rep about using the Kemper Power Rack without a load on it and he got that information from another sweetwater tech that he claims knows the products well. That's as much as I know .Maybe someone can confirm if this is the case or not .
I don't think this is accurate, as I'm not using the power amp in mine right now and toggling the amp on and off has no effect on the sound through my powered monitors.
Agreed.
The best thing to do is for me to ask the Kemper tech support to find out .When I have time , I will try recording direct to my interface with and without a speaker load on the Kemper and see if there is any difference .Either way, it is a solid state amp and having no speaker load shouldn't hurt it .
Surely it would be illogical to me that the sound changes with the power section switched on/off.
Can't be true.
If you dont use the KPA with a guitar cab you can switch off the power amp under output section on page 7
CoolI didn't know that
Welcome to the forum, Ian.
I see Ingolf and others have already answered your questions.
Not to be "that guy"...but I highly recommend you familiarize yourself with the KPA Basic and Reference Manuals. After you have read them, read them again. 
From one of the sales reps at Sweetwater Sound .I asked my sales rep about using the Kemper Power Rack without a load on it and he got that information from another sweetwater tech that he claims knows the products well. That's as much as I know .Maybe someone can confirm if this is the case or not .
[Blocked Image: http://i.imgur.com/iWKad22.jpg?fb]
That facepalm wasn't mean't for you, Paul. It was for the boneheads at Sweetwater. And, I love Sweetwater, by the way. However, they are completely wrong on this matter.
The best thing to do is for me to ask the Kemper tech support to find out .When I have time , I will try recording direct to my interface with and without a speaker load on the Kemper and see if there is any difference .Either way, it is a solid state amp and having no speaker load shouldn't hurt it .
Paul, here is an excerpt from the Kemper Reference Manual 3.2, page 21:
-----------------------------------------------------------------
The Built-in Power Amplifier
The optional built-in power amplifier allows you to connect your Profiler to 4, 8, and 16 ohm guitar cabinets, as well
as passive full range cabinets. It is internally cabled to the MONITOR OUTPUT, so all features of the MONITOR
OUTPUT are applied to the internal power amplifier as well. Please refer to the chapter Monitor Output of this
manual for more detailed information.
You will find controls for the power amplifier on the dedicated page of the Output/Master menu:
Power Amp Switch
Switches the power for the built-in power amp. There is no specific need to switch it off when not in use; unlike a
tube power amp, the built-in Class D amp is not in any danger when you have no speaker connected. Still, you may
want to switch it off to reduce energy consumption.
----------------------------------------------------------------
I hope that clears up any confusion or questions.
Cheers,
John
P.S. -- I have a KPA Power Rack, and in the rare cases I am not using the power amp, I do make it a habit of switching it off in the "Output" Menu. Then again, I am one of those people who must turn off the lights whenever I leave a room for more than a few minutes. 
