You can read TONE on the iPad with Good Reader, but we are working on a premium version that should be available soon. We won't address the kindle or nook because they don't offer a meaningful translation of the magazine due to the bw graphics and inability to zoom the page.
You can get stereophile on zinio, and it reads well. I believe you can also get hifi news there. It's the way were heading, print just isn't a sustainable model for specialty consumer magazines for much longer.