A little history:
- the first one, NS-HD01, is perfect on every aspect - good reception and battery life, except one thing: it crashes frequently and need to push into the tiny reset hole often. So often that I had to enlarge the hole so I can inert the headphone plug into it.
- the second one, the same version as the first, does exactly the same thing. Then I knew, it was a common design flaw, not just a defective unit that I happened to buy.
- the third one, firmware 04.00.14, no longer crash. But, one day I heard a huge explosion from it while I was plugging it into USB charger, then it went to total silence. It still operates perfectly, just no audio. I tried everything, such as remove the battery, reset to factory, etc.
- so I bought the newer model, NS-HD02. It is totally garbage. Unusable touchscreen, very poor reception and battery life.
- once I saw the latest model, NS-HD01A, I bought it immediately, hoping Insignia have finally done everything right. It was perfect, for the first 3 weeks or so, then it went into DOS exactly like the third one.
Hopelessly, I opened the NS-HD01A to see if anything I can do, like the old Chinese saying: cure a dead horse as it is still alive - nothing to lose but probably a chance of gain. As soon as I saw the Cirrus CS43L21 D/A chip, I knew exactly what's wrong. I brought it back to life with a short wire. Then I added a component, to avoid the DOS problem forever.
I also did the same to the third one, the one with 04.00.14 firmware. Now these two have been working perfectly for several weeks now.
I also tried to fix the 1st and 2nd ones, in vain. They use an earlier version Cirrus D/A chip, CS42L51. This chip has a lot more functions than the newer version.