Playing your recorded MD in a full size MD deck with native digital output seems best way to transfer the 16bit/44.1K digital audio directly to computer soundcard with minimal data conversion as has been discussed.
There are very few shelf size MD decks being sold new with digital outputs these days, and these are quite expensive Sony models meant for musicians. Best bet is to find a used consumer deck with digital output, and try one or more of your discs first to assure it is played correctly by the prospective deck before buying.
Least expensive USB soundcard found usually works as well as the most expensive card for this purpose, as long as the soundcard does NOT perform resampling as is typical of Creative soundcard models that resample everything that's inputted in digital form (these are NOT bit-for-bit accurate as a result of this resampling).
M-audio Transit USB connected soundcard does not resample, is <$100 new, and has ONLY optical Toslink input ability so make sure the MD deck has optical SPDIF digital audio output feature if using the Transit.
Other USB type external soundcards have RCA connected coaxial SPDIF input, few have both Optical AND coaxial input, and same for MD decks that typically have only one type output so make sure both match up.
Alternative to using a USB computer soundcard is instead using the M-audio microtrack or another make of flash recorder with digital input recording feature. Then MD digital audio is transferred directly to be 'stored' in a flash memory card that can be easily read by USB connected flash card reader by the computer, and no computer soundcard is needed in this case.