The K701 and the Grados suffer from the same condition, which is fatal to some and practically nonexistent to others. The open sound lets the bass leak out. It's an intentional design flaw because both cans strip away a lot of resonance while letting the bass get away. The result is a very clean, detailed sound but one that can't command a very booming bass presentation (assuming you'd want one).
So, how do you get such clarity but also get decent bass? You buy an amp, a good one, preferably one that boosts the bass in a relatively clean way. Distortion in bass is less critical an issue than at the higher frequencies. The LF waves that would appeal to a basshead are not the kind one can make out very clearly to begin with. They're long and slow. They work just fine in mono because they're multidirectional and awfullly hard to hold up in stereo. If you want a clean, tight, controlled bass, you probably don't need overkill. But if you're listening to something with more of a club mix than a concert-hall arrangement, bass boost does a good job of looping and multiplying the frequencies within its crossover cutoff. I'm not sure what needs amplification beyond 100 Hz. The rest is fine as it is.
Purists will complain that this is a violation of the integrity of the original track. But so is the loss of that bass out the back door of an open-air design. Bass boost is the attempt to compensate for signal loss. To be sure, I'm speaking as one who values the upper register more than the low-low floor, the sub-100 Hz finger of God. Most of what I listen for is well covered by both the Grados and the K-701s, just as it would be with a pair of Magnepans. But as owners of Maggies know, you don't get deep bass out of an open-air speaker. You get a more transparent presentation. For that deep and slamming full-bodied bass, you either go back to cave cans or boost the bass signal to fill out the low end.
I don't lose much sleep worrying about it.
