Sounds to me like it could of been a constant current source/ Fet in that channel.
Audio Research LS2B: hissing noise from a channel
I was trying to mod my Audio Research LS2B following a few treads that recommend replacing MIT Multicaps caps with Dynamicaps. As suggested, I turned the Dynamicaps in the left channel in the opposite direction and turned the preamp on: what a surprise! After a strong puff sound there was black smoke coming out of the Dynamicaps. I then turned them around, and also replaced the caps in the right channel following the original direction of the MIT Multicaps (with 2 new Dynamicaps, I got 4 of them), and the right channel works great. However, there is now only a strong hissing noise coming out of the left channel. Would anyone know what did I blow in the process? A MOSFET, the Sovtek tube? The sounds in the right channel has a significant improvement over the Multicaps, but now I don't have the left channel. Can anyone help? Thanks in advance.