I have hum on my HA-4700 headphone amplifier. Channel one is ok, but the hum gets progressively worse through channels 2-4.
It is present even when the volume controls are turned down. It is NOT an earth loop or cable problem as it hums when it is connected to nothing except the mains supply and a pair of headphones. I have tried using a power conditioner and in a different room away from the studio.
From reading posts on the Internet, it seems it is an inherent problem with this unit, so is there a modification or fix available or is this just the way it is? That would be a shame as the quality of sound is superb, much better in fact than the more expensive ART Headamp 6 pro which sounds dreadful by comparison.
I use several pairs of very good headphones, Sony MDR-7520, MDR-7509 and Sennheiser HD25-2 and listening conditions are quite critical in a broadcast radio production studio where we often record speech only programs. Several people, especially those connected to channel 4 have commented on the hum.
Noise figures quoted for this amp are -90db, on channel one possibly, but every other channel no way!
Sorry for bumping an old thread but I wonder the same. Is there a fix to the hum of this headphone amp. My story is that I bought one long time ago. Sent it back to store wich if I understood it correctly sent it to some behringer service center. Got it back but only slightly better. Sent it back again, this time unit got scrapped and a new unit was sent to me. Now I sit here listening to the same hum, this timeat least there is two usable outputs and two hummin.
Really sad as I have very much behringer products that I´m really pleased with. This unit though... To bad that Les mentioned the Art unit sounding bad as I was considering gettin that instead.