Hi,

I recently bought this Torii II amp from a guy on agon and while the amp appears to be in excellent condition and sounds superb with my custom single driver speakers.

The one ongoing problem is that there is a fixed, low-level hum coming from both vhannels, but slightly more of it from the left channel.

I've done everything an experienced tube audiophile would do, including swapping tubes, cleaning sockets, disconnecting sources, re-routing power and signal cabling, etc., but the hum persists.

I can hear it at a low level sitting about 7.5 feet away and while generally not audible for a lot of music, it is quite prominent in quiet passages in some orchestral and acoustic musics.  Bottom line is that it shouldn't be there, and I'm out of things to try with the exception of an isolation transformer to block any potential DC on my AC line.

I have also not heard from Decware on this since the last email which simply pointed me to the link to the white paper on debugging hum issues.

I suspect that the transformers are buzzing a bit (as I can hear them) and rattling the elements of the rectifiers and possibly the output tubes because after all the tube swapping, etc. the only thing that made any difference at all was going to a heavier gauge, shielded power cord, and that had only a minimal positive effect.

Are there any known problems with this amp and AC power with DC offset, or do I have something seriously wrong that will require me to ship it back to Decware.  Either way, I'd really like to get on with this because I am ultra sensitive to hum and hiss problems -- and it's been a long time since I had a tube amp that did either.

Thanks,

Jim

Believe it or not, I actually had an intermitent hum with the Mk II that I finally traced back to the electronic light dimmer in the room.   Totally seperate circuit too.  I could hardly believe it when I found it, especially after all the work isolating everything in the rack.

Jason