TWO kind of solution right now,
1. ALI M5667
2. unknown (will open and take some photo after the test)
Test:
1. Read / Write Transfer rate
2. Frequency response
3. S/N ratio
4. Audio hole test (MP3 player must have this test)
5. Compatability test (diff. MP3 bit rate, format)
6. Power consumption by daily use. (approx operating hour)