Needs Work & Support
I tried their free apps and they seemed pretty good, but missed the sound feature. So I bought it, and the sound feature doesnt seem to work.
I tried to go to the web site of maj9.com to look for assistance, but both links in iTunes, and entering the URL manually, just try to load iTunes to take you to one of these pages with no other information than the app advertisements.
It has some really good features, but I recommend you stick with the free separate apps until they fix this one and provide some support for their product.
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Guitarist's Reference, v5.4