.oma is a Sony proprietry format. Switch can only convert the older Sony ATRAC format (.wav)
http://www.nch.com.au/acm/formats.html
http://www.nch.com.au/acm/support.html#OMA
http://www.nch.com.au/switch/kb/747.html
All our software is available for free 14 days trial so you can be sure about your purchase before handing over your hard earned cash. Once you purchase and register your software your asked to tick a box that confirms you have tested and the software does what you want which voids any refunds.
Its still a great bit of software and im sure you will find use for it.