Hi You Two !
Redmaw first, The Senn 650 are open back so leak sound as do the AKG. I am surprised you cannot find the Senn at the same price as the AKG. I actually paid less for my Senns than my AKG. Both brand new.
The Senn 800 are pretty difficult to drive as are the AKG [despite their faily low impedance they are inefficient] but you are right when you say a decent headphone amp will do the trick. The Yulong certainly will not struggle . It has an optical in and you are correct to think , as a generalisation, optical will be better than USB. I am awaiting delivery of a Decco2 however , which has optical as well as USB and here the USB is said to sound as good. The Decco has a great Dac, great headphone amp [which can be used as a tube amp or solid state] It also has a great preamp function so you can feed it into a second amp and also has a decent 40 watts per channel amp so you can hook up suitable speakers [ie not very high impedence] directly to it.
It is a fair bit costlier, $800 , but I needed a second system and fancied the sound of it. I will post when it arrives and give you my thoughts. Having said all that, I can unreservedly recommend The Yulong. It is a clean, detailed presentation and I would be very surprised if the Decco sounds much better. I just like the idea of running my speakers straight off it and like the idea of a tube function. The tube should slightly alter the sound.
High bdbjr,
I think , as I said earlier, If you listen to heavier stuff then the Denon would be a great bet. They have superior basss to the AKG and a really nice up front presentation which brings hip hop to life. I prefer my AKG for jazz and light acoustic stuff. I play Jack Johnson, Ben Harper, Richie Havens, Joan Armatrading, Madeleine Peyroux etc etc and the AKG does these better.
As regards your sound card it sounds like it will be fine. As we said, if your PC struggles to drive the Denon, just boost it with the preamp function of medimonkey and you will be OK.
The Denons , however are a lot easier to drive than the Senn or the AKG so you will probably have no trouble.
As regards my Atlanta music, I am a 54 year old guy who grew up in the North of England when American soul music became a big thing. I started going to clubs when I was just coming up to my 15th birthday and was weaned on soul. We also listened to Tamla, as opposed to more hard core soul. When Stax did a tour in the early seventies , the artists [ Otis Redding, Sam & Dave, Wilson Pickett, Don Cavoy, Rufus Thomas, Steve Cropper etc ]could not believe how much we knew about their music
I am also very into blues.
Nowadays my tastes are more varied having Florence and the Machine, Lilly Allen, Kings of Leon, Euphoria [ electronic] alongside my blues , R & B , Soul , Jazz and a good smattering of pop music. I used to malign pop but have come to realise that actually there are some great pop records out there, you just need to find them.