I’m running a little dot MK4 as a preamplifier for my s300. After using a rothwell line attenuator to fix the gain mismatch, the results are sonically excellent with one problem I can’t resolve. There’s a constant low level hum which my ears say is a 60hrz hum. It’s not affected by the volume and is equal in both speakers. The kicker is it’s present when the little dot is switched off as well as on. It’s definitely the little dot because when I plug other pre amps into the system it’s silent - the hum only comes back the moment the LD is connected - even powered off - the connections are the same - I just remove them from the LD and plug them into an alternative device.
I’m non technical, but I’ve tried any number of isolators and socket switching assuming this might be a grounding problem, but nothing works.
It’s low level, it’s not really noticeable from listening position but audible next to the speakers. Because you know it’s there, it’s bothering me more than it should. In all other respects the LD is superb looking and sounding when partnered with the S300 - my view is you so need the rothwells in the chain as well.
Any suggestions to fix this?