The rep at the Saratoga meet was the differences between the K701 & K601 were "slight". I didn't hear them then, but last night I was at Voltrons house and he has both (K601 burned in, K701 new). Unless the K701 losses breath and soundstage with burn in, it's really hard for me to believe most would find their differences to be minor. People may actually prefer the K601 more enclosed sound, but to no matter your preference they don't sound the same.