The 18 is in a CIEM class of its own where it is comparable to the Utopia and other full sized exotic HPs. The times that I have heard the Utopia was on an extremely tweaked/expensive setup which really made it sing so I am not sure how it would fare on lessor systems. However, in comparison to the Abyss or LCD4 sitting next to it, the Utopia felt bass light reminiscent of the HD800. What made the Utopia special to me was the clarity and natural mids along with detailed and smooth treble which was all drool worthy. Think of the 18 as a Utopia tuning with the addition of world class bass. In addition to the bass advantage, the 18 can be powered by an iPhone or DAP and provide performance levels equivalent to the Utopia driven by total systems. Obviously the 18 has more versatility, but if you have the total system to drive the Utopia and it is being held back by your current HPs, the Utopia is a great choice too. It really comes down to your use case and how important bass is to you.