A bit of a odd request. Here's hoping it's viable.
The character themes for the Persona 4 themed arcade 2D fighter have recently been ripped straight from the arcade board and uploaded into Nico Video and eventually to YouTube.
This playlist has them Persona 4: Arena OST - YouTube (http://www.youtube.com/playlist?list=PL943504FF3458A7B5)
And this channel has extended versions of most of them Bossadai776's Channel - YouTube (http://www.youtube.com/bossadai776)

Any possibility of converting these to MP3 format while maintaining the quality? Most free software I found seriously downgrades the quality so I turn to the specialists for help.

Thanks in advance.

Why not convert directly from Nico Nico? If so, then use this link; http://nicosound.anyap.info

Thanks for the suggestion. I decided to give it a whirl from this tag list - http://nicosound.anyap.info/tag/34ecr every theme but Kanji's and Teddie's at 192 kbps.
I don't know if there's any nuance to that page though. I just saved the mp3s files.
Uploaded it here > P4A.rar (http://www.mediafire.com/?kxh9zsoluii1a8k) (kinda ironic to put download links on my own request topic)

Obviously, this is by no means a "definitive" rip. Just something to keep our Meguro-loving ears busy until a official soundtrack is released.
I'll wait to see if the "pros" have anything to say in terms of quality. (And I confess I was kinda itching for the extended versions of some of these tunes.)

Thanks once again for pointing out that link. I found it weird that with so many people uploading these tracks, no one bothered to leave DL links.

EDIT NOTE: for some reason the Nico video links for the themes of Kanji, Teddie and Labrys don't provide a mp3 download link when submitted to Nicosound.

try also nicozon & nicomimi