Nuforce STA200

My STA200 was/is dead quiet.  I am told some systems could have a gain issue which from what I understand means that if you pair the STA200 which has a high gain with a preamp having high gain you can end up with the hiss you mention.  One fix for this is a Schitt Sys passive for $49 between the amp and preamp.  Its set once and forgotten.  Unfortunately it does not sound like you have time to work through all of this, and really may just have a "bad" amp and not an gain issue.  If I have this wrong someone please jump in and correct me.

My STA200 is also dead quiet. Have used it with two speakers of 6-8ohms, 87dB for limited hours as it is new  Might be a compatibility problem with your preamp. Does hiss get louder as you turn up volume? Usually a gain driven hiss problem becomes more a concern with highly sensitive speakers. That said, I would not choose this amp for use with a speaker having an average load of 4ohms (see discussion above). 

I've had no trouble with 4 ohm speakers...currently Dynaudio Focus 220 mkll...

Jl35, that is good to know. The speakers I own are rated higher than that, however do drop below 4ohms in the bass region. Phase angle at these frequencies is benign however. In what size room is your system?

smallish room, about 12x14...I think the amp is fine into 4 or 8 ohms, as long as it is looked at as a fairly low power amp, which is what it was designed as...many amps put out same or similar power into 4 or 8 ohms, such as McIntosh...