I suggest researching the algorithm Wadia employs to fill the empty space when they up/over-sample (spline fits). I havn't seen a company out there that uses anything better to improve the resolution of the signal in the time domain (disclaimer: not all companies list what they use, though most just use empty space; there might be a few that use algorithms to improve the resolution like Wadia does).
After doing the research I would listen to both as well, if you can.
After doing the research I would listen to both as well, if you can.