@bob52r I am a Lyngdorf fan. I own a 2170 which has made my living room system more than adequate in a room with miserable acoustics. I've helped 2 of my children assemble 2170 based systems in rooms that are less than ideal. The 2170, and I presume the 3400 as well, can be an ideal solution where one is not able to utilize extensive room treatments.
In your case, I might well go in a different direction and assemble the best headphone system I can, unless your stay in an apartment will be very short term and you are pretty certain about what kind of music room you will have long term.
If that won't work for you, then going with one of the Lyngdorf integrateds with Room Perfect might make sense. I cant comment on the quality of the headphone out. but I will tell you that if you want to build any kind of decent vinyl system, you will need a separate phono preamp if the one that is in the 2170 is any indication. The one in all three 2170's I've had access to is unacceptable.
I think the genius of the Lyngdorf is in its ability to take a digital in signal, by USB or coax, and keep the signal in the digital domain until it is output to the speakers.
Dealer support being what it is (or isn't) you might want to buy a used one and try it. If it doesn't work for you you can resell it without taking a bath.