I was reading through the manual of the Sunn 300t and noticed it has a cab simulator on the DI line out!? Can anyone comment on this - I've used the H&k Redbox but that just seems to rolloff the upper register a bit? This is the first time I've seen this on and amp's Di out...Is it any good? Have they included this in the new fender version? Everyone seems to say the origional Sunn version is better, what is the actual difference?