Trust Mauro USB headset

Trust Mauro (17591) USB headset, retail price ~$20.

Problem: weird sounds from left earpiece (not correlated with played audio), slightly disturbed sound from right earpiece.

Rather big in size in-line controller: volume, output mute, microphone mute.

Sound card (chip with scrapped markings) inside USB plug. Plug itself is glued together but can be opened by prying (with some damage).

Cause of the problem: mismatched connections between USB part and controller part. I think this was factory error, probably partially caused by not so clear PCB markings (for example there is "M-" and "M/-" contact pad).

Build quality is worse than with Trust Roha - headband is thin and little creaky, ear cushions are less soft. In-line controller is large and its weight can be felt when e.g. it drops from the table.
Probably too much bass (same as Trust Roha), but not as muddy - they sound better than Trust Roha.

On the other side microphone is quite noisy. It seems that this noise depends little on USB connection - it was higher when I was using extension cord.

One weird thing is that sound card emits some heat - not a lot, but this is still unusual for this type of device. I'm not sure if this is not a problem of my particular item, but otherwise it seems to work correctly.