First of all, I prevent what I use guitar rig 5 for recording… I know what it’s not same but it works
I just want to know about how does it sound - to use a combination of jazz amp with metal distortion in a real-life? In gr5 this combo I really like because it gives me a beefy dark tone with cool attack, kind of middle between punk and metal tones. So, send your opinions, or knowledge about this
p.s. Sorry for grammar mistakes
I had an RJC for a long time. At school trying to emulate Pat Metheny. I had an old TS9 hooked up just in case I wanted to wail. Amongst a few other incidental pedals. For clean stuff it is the best. But it never breaks up so it’s crud for dirty stuff. I’m sure some people will love the super cleans though. It’s a legendary amp.
Interesting idea, I usually like an overdrive pedal in front of a clean amp so I’ll give it a shot… But not with the real thing I’m afraid, I also use amp simulators 
Amp sims these days, unless they’re truly awful, are usually good enough that, if you like how something sounds with an amp sim, you’ll probably also like it with the real amp. It’s rare to find an amp sim that sounds and responds nothing like the real amp.
As a guy who’s owned a JC120 since longer than some of you have been alive I use a Mesa Studio preamp as the front end. Works pretty darned well to get that high gain distortion thing through an amp renowned for being squeaky clean. Another suggestion was using a boost. I used to use the TC Electronic BLD to do the boost and the JC would distort like it seldom does. I think any clean boost with a 2-3 band EQ would do the job.