Oh, yes I did it, I'd tried all the outputs with my monitors, with an amps and with a cab (to the Speaker output). There is no difference between them each time.I made some recording pluged in SPDIF : These rigs come from the KPA from origin :
I can understand that that is not everyone's tone for sure. It wouldn't be mine if that matters.
That being said, there are differences between tube amps and the Kemper, plus some people are more sensitive to certain frequencies than others.
In your example, I'm not hearing anything like a cheap transistor amp and I grew up in the 80's, so I know what cheap sounds like haha
As Dimi84 said above, you may not be digging the "original amp tones" (and as I understand it, how the original amp was mic'd up) but you may not be digging a certain frequency in the profiling as well. There are discussions on this forum about that. You may not be digging the mic'd up tone vs the room sound. That is just something you may want to consider as well.
As a reassurance, I wasn't entirely happy with the factory presets. And if those were the only ones available I may not have kept my Kemper (*). That being said, there are a lot of very very usuable tones on the Rig Exchange/Manager. And there are many great commercial profiles out there.
(*) Tones are subjective and the presets are great for sure, so I'm not knocking them
Hope that helps.