So I've been listening to the HD650 acquired this week given the latest Amazon price drop. These are NOT the HD650 I heard several years ago.

My HD600 have been a constant over the years, with the HD580 for a considerable time before that. The past HD650 had more bass but sounded thick and dull to me compared to the HD600, tested on various amps. The HD650 to which I am listening today are neither thick nor dull. They sound very very good. In fact I have been listening for more than four hours today (a recreational listening day, yeah!)

The last two hours have been with a Mousai MSD192, Project Sunrise III with PSVane 12AU7, output set for 32 ohms. I will be wanting to do a system level set of measurements to find out why this modest setup sounds so good to my ears.

Thanks for the help guys.  We have a soldering station in the lab here at work so this seems like a good opportunity for me to learn some basic skills.    (There are also guys here who can probably help me if I fuck it up)

I'm thinking I will do a shootout of new HD650 vs my (late 2014) LCD-3F.  I really enjoy the sound of the LCD-3F (I think I have a good pair?) but the comfort issues are wearing me down over time.  I can only wear them for maybe 30 minutes before the "hotspot" in the middle of my head starts to annoy me.

I burn the teflon strands off with fire after separating them.

Proly depends on what you are used to. I find the Lambdas inferior to the HD650s in many ways. The Lambdas are perhaps a tad brighter relatively speaking. I don't think the Lambdas are as resolving. Bass would definitively depend on cup fit and is lower than with the HD650s going by memory.