It has worked as intended for a couple of years, no disturbances
That box is also a Linux-server(DLNA, HTTP etc.) so it is on 24/7!
I mostly use the line-out of the ST(X) feeding an old school HiFi-stereo setup which works as my "PC-speakers", I have experimented some with OP-amps and ended up with swapping one of the JRC2114DD:s from the I/V to the buffer, and using two LM4562NA:s as I/V instead. That gives me the most "live" sound over both speakers and local heaphones. The headphone out is just great imho!
I've never thought about a DAC, since the ST(X) sounds good enough that a "better" DAC would cost too much money.
As the box is a server, I play from it using wireless on my other appliances like Home Theater and Smartphones and of course they have their own DAC:s of varying quality, good enough for their use though(my HTPC actually uses optical out to it's receiver, so no exotic sound card needed there). However, in example the Galaxy S5 has a too weak HP out for my taste, so I often use a Topping NX-1 portable Headphone Amp on the move
I use another PC(Windows) for gaming and such, the "music" box is pure Linux!