I have a lot to say about this topic
Although the worst ones are not music hardware. Lets begin with music hardware:
- BSE (or BNE or something beginning with B) DJ double CD-player (Denon clone). Can you believe that pressing rewind or fast forward the unit was actually thinking for over 10 seconds before starting to rewind or fast forward

, no wonder my DJ skills development was very slow in the beginning.
Non music hardware:
- the worst piece of hardware I have ever bought in my life was Fujitsu-Siemens Amilo A1630 laptop. They had to change its motherboard 6 times inside 6 months! Most of the time I didn't have the laptop but it was in maintenance. After that I reclaimed and got a new Amilo.
- the second worst is Nokia E70 cell phone, absolutely nightmare with so many problems and bugs that you wouldn't believe it. After that I had Nokia E75, the amount of problems halved but was still unacceptably high.
- IBM 40GB Deskstar (aka "Deathstar") hard disk. I bought two of them and in 6 months they went broken 3 times.