The mark iv is far more versatile than the 2C+ . The 1st version is more raw and in your face than the 2nd one which is more modern / compressed and has more gain. Personally, as much as I enjoyed all the 5 mark iv amps that I had in the past, I still prefer my mark 2C+ amps. There is indeed sth amazing going on with the complex harmonics thing that cannot be described. Only if you A B them closely will you be able to understand and hear the nuances. But it goes without saying the mark IV is one of the best amps money can buy (at least when the price is fair lol)