Any suggestion for dead quiet tube headphone amp

I almost always had preference to SS headphone amplifiers due to the reasons you've described above especially when you have a very detail oriented headphones as AKG K701.
Don't know your budget, but I bought used Consonance M20 on the way to be shipped to my home to try.
I got it for the very descent price, but functionally this headphone amp has only one input and neither bypass output nor another set of inputs.
Well, if infact it would work sonically and noisewise OK for me, I'll plan to DIY add another set of inputs or even bypass output. Otherwise -- straight-forward sell it and to Grace Design M902 as this piece can sound like tubes or even better. Very pricey though and hard to find used.

Have you auditioned the STAX offerings?
How much do you want to spend?

Got my Opera Consonance M20 yesterday and couldn't stop listening to it.
Excellent drive, bass and quiet.
I connected it directly to my Alesis ML player/recorder at first and even listen through its recording interface when I played records.
After I decided to reconnect Consonance to the tape output of my preamp Classe30 and connect my Alesis balanced to the preamp and there heaven had begun for nearly 5 hours of continuous non-fatigue listening! That darn thing simply sings! I only regret that it doesn't have bypass out, but that's going to be my project...

www.raysamuelsaudio.com
www.headamp.com
www.ttvj.com
www.eddiecurrent.com
www.hollowstate.netfirms.com
www.wooaudio.com
Also some amps on ebay from Little Dot and darkvoice, but these two i only know from reading about and have not heard.
Lots of them out there. Lots of info at either www.head-fi.org or www.head-case.org

Thanks for the responces. I was thinking budget, like under $300 used?? Tweaker

FYI, I settled on the Elekit TU-882. Extreamly quiet. I now use the Russian 6n3P-e from 1976. Very nice amp.