Converting for eventual transfer to MD

I listen to a lot of old time radio. These mp3s are encoded at very low bit rates, usually 32/22. To get these files onto a minidisc I need to convert them. I can either keep them as mp3s by changing the 22Khz (frequency) to 44 Khz or I can convert them to wav files. My question is, which of these two methods would end up with a better sound when eventually transferred to MD?
Does dB convert an mp3 to wav and then back again when changing that frequency? If so will there be noticable loss of audio quality?

Any encoder will have to reencode the file to upsample the frequency which would give you a loss in quality. If possible, try and decode them to 22Khz wave and see if it will let you use those because all it is a plain decode without any frequency conversion so you don't have to rely on Windows' ACM resampler or dMC's PFC or any other middleman in between that could hurt the quality.

Considering that the file is encoded at a very low bitrate, there probably isn't that much quality to begin with but it might be hard for MP3 to reproduce the same quality again at a low bitrate if you reencode because it will be trying to reproduce the file's content and artifacts and will be introducing its own in the process. Add to the equation that whatever is served up to the MD will be reencoded to ATRAC3 at 224Kbits/s (SP), 130ish Kbits/s (LP) or 60ish Kbits/s (SLP) and you could lose a fair bit of quality.