BillinSF
100+ Head-Fier
As silly as this sounds, I had hiss in my system and eliminated it when I realized it was coming from the fluorescent under-cabinet lights in my kitchen downstairs which I turned on after dark. I now make sure they are off when it's music time.let amp ma
I don't have a specific knowledge of this amp, but yes in general a converter box may eliminate the hiss. So may a passive filter cable on the heapdphone side (can make custom for any terminations, e.g. https://diyaudioheaven.wordpress.com/passive-filters/)
that said, it may be worth understanding the source of your noise and elimiante it, as the above may have mild trade offs for the signal path
I'd check the following:
(1) How clean is your power source -- try adding a great power conditioner (here, too, experimenting has different results in quality; but reduction in noise will let you know this is the issue and you can invest further)
(2) Are any of your cables subject to EMI or RR interfernce?
>> If you have any tube components try to distance them a bit, same for computer gear, cell phones, other electronics. And same for power sources of compoenents
>> Check how well shielded your interconnects are. If you are using any RCAs, trying to replace them wtih XLR if possible. If not, and either case, try to create distance between all your various cables, and if they have to cross each other's path, ideally at right angle (rather than bundled in parallel and close to each other)
good luck!
As Goldwerger says, its all about clean power.