SQ or QS lp can be transfered to digital with any stereo soundcard, no extra hassle involved.
After that you can run the Adobe Audition script for the software decoding, which is at present time the best option, then do a dts cd or a dvd-a or a multichannel wma or flac.
So, it's not a big problem by itself.
Maybe knowing two things can ease out the question:
1) what do you have and want to be converted
2) where you are.
Why:
1) lot of quads are already converted in some format, so if the hard work has already been done, why do it again?
2) here we're from at least 4 continent, so it's hard to guess if there's something close to you without knowing your location.