I’ve been working on this for my site and you can, if you use soundcloud.com. Create an account, upload your mp3 there and then share it, copy the embed code. Now in your portfolio post click the add external video by url button and paste the code in. Soundcloud Embeds like youtube or vimeo oEmbed or whatever it’s called. You can edit the widget that is created in soundcloud. I’m still working on making it look right, but it plays. Hope this helps.