Best/easiest way to convert wma files?

I have about 95,000 wma music files on a 2tb USB drive that my Aurender N100 cannot read.
Any suggestions for converting them or is that a non starter?
Many thanks.
Hi Uberwaltz,

A program I am familiar with, which I have used extensively for various amateur purposes, and which can "batch convert" files in pretty much any audio format to any other audio format is Sound Forge Pro. As the name suggests "batch converting" means that once the files are specified and some parameters are entered (such as the format and location to which the files should be converted and saved), the program would run the conversion process on all of the files unattended, for as long as it takes. And in doing so it would create new files in the desired format, without affecting the original files.

The program costs $399. However it can be downloaded and installed as a 30 day free trial, and although I’m not certain I suspect that the trial version would provide the same functionality as the purchased version during those 30 days.

If you choose to do that, once it is installed you can find the "batch converter" function under the "Tools" menu at the top. When you open the batch converter click the question mark in the converter window, which will open a helpful guide to using that function. (You can ignore some of what it says, though, relating to processes and effects, since all you would be doing is converting the format).

Good luck. Best regards,
-- Al

If you’re comfortable using command line Windows Audio Lossless to Wave Converter will do it as a batch job. You can download it from Microsoft. 
Thanks Al
Just completed a test batch of 500 converted to flac and all is well!
Reads them just fine now so.....
only 94,500 to go......
Using the trial version of sound forge pro as Al suggested.
First test batch of 500 went well and did exactly as I wanted.
Started the complete hard drive conversion last night, 12 hours completed, 11 hours to go... lol.
Uber, it looks like you have this figured out, but foobar2000 will also do batch conversions and it is free.  I use it to rip CD's and listen to all the music on my network.
The Windows Audio Lossless to Wave Converter is free as well. It's mainly for converting wma to wav. It might have  done it slightly faster since it doesn't have a GUI but any that gets  the job done is all that counts.
I have all the great suggestions saved, it is much appreciated.

Tbh, the time is no biggie as off this week and just letting it do its thing in the background.
I think flac files take up less space than wav though.
And it looks like my 239gb WMA files converted to flac is still going to overflow the 2tb hard drive!
Just bought a 4tb hard drive to transfer to later.
All done and now have over 6000 albums to explore.
Quick glances show not too many duplicate of my own collection.
Enough to last me a few evenings I would say.......

Thank the Lord for CMD batch file extension delete to get rid of all the left over WMA files on the drive.
Less than 30 seconds for the PC to wipe out 95000 WMA files , impressed!