I have owned a pair of K-701's for a couple of years now, and I LOVE 'em. My break-in was at LEAST 100 hours.
I finally got off my duff and got a portable headphone amp for them (the headamp AE-2), and I now understand why most people recomment the use of an amp with these fantastic 'phones.
While I was never disappointed without the amp, the K-701's truly come alive with a bit of 'oomph' behind them.
My needs limited me to a battery-powered amp, but most people highly recommend tube headphone amps with the K-701's.
I look forward to hearing your impressions, and CONGRATS!
Warmly,
Michael