A tale of breathing life back into the K340
Wow, I couldn't believe I am now digging up this fossil of thread!!! Almost 9 years ago, my relationship with the K340 started with this thread. After a long time away from hi-fi, I came back to it this year, trying to build a system around the K340 again.
At first, I organized a local meet, where I tried to drive the K340 directly from the Geek Out V2 + balanced output, the sound is... thin as a piece of paper

I knew there's no way a portable amp could handle this beast.
Later, I got around, bought a vintage Yamaha CA 800 II integrated amp with 15W of sweet class a power

, and the new Matrix Mini-I Pro DAC to try to bring the beasts back to life after being shelved in a closet for so many years. At first, I wasn't happy with the result: too bright trebles, and very thin bass. I knew something drastic has to be done

Then I looked back into this thread for more inspirations to mod them. My final mods are as follow, but keep in mind that my pair is the bass-light version, so my goal was mainly to build up its bass:
1. I got some foam tapes (for water pipes, I think. I just found them under the sink at my house), and I taped them in the headphones' plastic housing. Basically, I was under the conclusion that the back-waves are what's killing the bass. After taping up nearly all areas of the housing (just about one layer, not thick at all), I left the openings alone. Even though I read that taping them up could bring up the bass, I do not want to lose the open sounds of the K340.
2. I reduced the cotton amount by half, and basically create a ring around the dynamic drivers, making sure to not block them from the openings.
The above two mods already gave it more bass, but still not quite as much as I wanted. But then my friend has a pair of Sony MDR Z7 stock pads that he no longer uses, because of too much bass. I thought, hey, may be that's exactly what the K340 need. But the problem is that they can't stretch over the headphones, so, I just used some double-sided tapes, and taped them on directly, and OMG:basshead: The bass is ALIVE! Wow, I didn't know the bass-light version is capable of such bass! Warm, detailed, deep, and punchy all at the same time! Of course, the treble got muffled a little too much, so to compensate, I turned on the fast filter setting on the Mini-i Pro, and all is good

D
Right now, every day when I listen to them, I smile from ears to ears. They are now detailed, airy, warm, and deep at the same time! I think the biggest difference really comes from the Sony's pads! I wonder if you guys can find them on ebay or something, because it really did the trick for my bass light version. So, here are some pics: