Lots of interesting stuff in this thread!
I have been using this rig for over 3 years now, which corresponds to almost 400 activations on three continents in different climatic conditions. I have also used it unprotected for extended periods in pouring rain and sleeting snow. When I opened the case once to check for debris (I didn’t find any), I, like @RX9WT, expected to find some sort of rubber seal around the case. I would describe it as water resistant, but not waterproof.
Fortunately I never had a failure, but I did experience some RF audio feedback on the 17m band and above when using my EFHW next to the TRX. My solution was to connect a CMC to the BNC antenna socket of the TRX, as I explained in another thread, where I linked to the QRP CMC, which seems to be available again. Other than that, I don’t use any other RF protection.
This rig is not perfect, but I like it for its robustness and ease of use. As I have only used it on SSB, the 48kHz wide spectroscope suits me perfectly, but I agree that this is definitely too wide for CW.
I was never interested in the BP-500 battery pack, and in IMHO it was wrongly designed for several reasons.
Back to the main topic about the TDA7056AT: On groups.io I read about several others that fried this (outdated) audio amplifier chip and it seemed that it also happened when only the speaker mic was used, but always after TX. Probably only Lab599 knows the exact cause…
73 Stephan