Hi! I wanted to share my experiences with the K340 for my first post here on head-fi
Back in the mid `80s I bought my K340 for newspaper route money. I A-B tested a lot of higher end cans back then and the K340 outclassed everything else, so I saved up for quite a while to get them. I was ~15 years old and living with my parents, I could not play loud music on my speakers at night. I drove them of a (still) very good Onkyo Integra amp and loved the sound and enjoyed them a lot for many years. When I moved out, they where put away and didn't see much use until now. Roles have changed, I now have a 3 year old and can no longer play loud music at night because of him. So I dug out the K340. I love them as much now as I did when I was a youngster. I realized that my livingroom amp didn't do them much justice, so after a bit of research I ended up buying a Audio-GD NFB-15 that I feed digitally from my Squeezebox. The Audio-GD is fantastic with the K340, the slightly warmish and detailed sound of the Wolfson DAC suits the K340 very well and there is ample power to drive them well.
I have been an audiophile in recovery (mostly) most of my life. So now I got upgradeitis and wanted more. these cans are over 30 years old and I thought that certainly there should be MUCH better stuff available now. So I set out to listen to what I could find in B&M's. I have listend to AKG K550, Sennheiser Momentum, 650, 700 and 800. When the salesman plugged in the HD800 into an expensive Hegel DAC/headamp, he had a grin on his face, like he thought I was about to be floored. He looked funny when my expression was only meh
I had high expectations for the HD800 and was totally underwhelmed. It's laidback mids don't do vocals any justice compared to the K340, there was also no musicality and joy of playing like the K340 has in such abundance. The HD 700 was much worse and even felt "dark" in comparison. I ended up buying the K550's as it does well with music that does not suit the K340's sound signature (sub optimal recordings) and I got it for half price. At 1/10th the price of a HD800, the K550 is great and can even be used streight from my Iphone when traveling.
I am a bit saddened that progress obviously peaked in the `80s, but very happy that my then rather large investment in the K340 still pays off in such abundance after more than 30 years