Headphones: can of worms time? looking at under $500

Do it! Go to AXPONA. It's your best opportunity to get to hear a variety of headphone amps and get to hear if any of them do what you're after with the Senns. If I lived within driving distance of an audio show like AXPONA I would absolutely go. There aren't any regional audio shows like that near me. But there are some local head-fi meets that happen in Portland and Seattle. A meet in Seattle is a 3-4 hour drive each way and absolutely worth it. It's the only way I'd get to hear some of this stuff.

I did a quick look at the exhibitors for AXPONA. They're going to have a dedicated headphone area. Unfortunately largely dominated by headphone and IEM companies and not many headphone amp companies. But still will be a good variety of headphone hardware gear companies. There will be some tube amps there, but looks like mostly solid state. Schiit will be there with all of their gear and amps. HeadAmp will be there and will certainly have their $3000 GS-X solid state amp. It's a very solid state sounding amp and worth listening to to find out what that kind of amp sounds like. I prefer a SS sound more like the Schiit Ragnarok, but you never know till you listen to both. Wells Audio will be there with some expensive SS amps. I've never heard any of them. They're probably good. Give them a listen to find out what they do. Linear Tube Audio will be there with the Micro Zotl and other amps. I haven't heard them, but reviews are good. ZMF will be there. He makes headphones, but will almost certainly have a tube amp there and will almost certainly let you plug in your HD600/HD650 if you ask. He also has nice DACs. Give his gear a listen. I like. He came to a Portland head-fi meet and had a nice pre-production in development tube amp. If he has the same amp at AXPONA it is a very nice tube amp at around the $1000 range. Listen to it if he has it. His headphones are also very good. I like. His idea of good headphone sound is in line with what I consider good.

Go. Listen. This is how you find out what this stuff is like. And whether it might float your boat. The amps and hardware used with the HD650 do make a difference and can transform the HD650 into something you find you like.

Bring your HD650 with you so you can try it on different amps as you go around, just in case the dealer there doesn't have a HD650 there for you to demo with. Most exhibitors will be willing to let you plug in your own headphones if you ask. Just be sure to ask first. And turn the volume knob down to zero before changing headphones. And leave the volume knob back a zero when you're done.