They may be soldered in, but I'm not certain.
The headphone socket will take a typical 1/4 inch trs plug or a 1/4 to 1/8 adapter.
I have one, it's pretty good and extremely well built. Two inputs and two outputs are very convenient as well, not to mention the pre-amp out if you have a speaker system. It's pretty detailed, not shrill.
I am selling it if anyone's interested, I travel too often to keep the amped setup, selling my recabled sextetts as well.
I just picked this up used off ebay for $180. For that price I am EXTREMELY happy with it. Powering my k271's it's pretty sublime. High's get pushed back a little more than I care for...but other than that it really sings. Very musical and "fun".
For anyone who interested HCMAUDIO<COM is selling these for 299.00 on a closeout. I almost bought one but went Meir Concerto all SS amp because of the power for the LCD2 but Shanling is the OEM for many companies and makes good stuff most notably their CD players