Nuforce STA200 issue. Rumble every couple minutes

@kray, it was designed to work with a passive preamp. @Mesch, it is not the perfect amplifier ( point me in the direction of " the one ", please ). Knowing it’s limitations, I bought my 1st one, and based on how much I enjoyed it, I quickly sold off locally, several other amplifiers I had in my large amp collection ( Mc 2105, Son of Ampzilla, Bedini 150, Hafler 200, B&K ST202, and a few others that I enjoyed,  and had good reputations. These were all up to spec, and they all had upgraded, heavier gauge power cables hotwired into them ( not a joke, when I tell you they improved greatly from this tweak alone ). I bought 2 more, to vertically biamp a pair of Signet SL280ex....an awesome system. I still have the speakers, but sold the two of the STA200’s, because I was down to one system ( with my Lascalas ), and felt someone else should enjoy them. I will keep my original STA200, as it takes up no room, and for what it does, it is a keeper. My best, Always, MrD. Enjoy !

Thanks @mrdecibel appreciate the response. I totally get that :)

But for me it's 3rd in line amp, and I'm not going to build a whole system around it, so my tube preamp/amps are first and are staying. My tube pre is only 6db gain, but with that and my high efficiency speakers I can't live with this loud hiss coming from my speakers (which is silent with my tube gear)

It sounds wonderful, so I will move it along to someone that can enjoy it in the right setup, and find a SS amp I can use as a third option that integrates better into my system. 

I’ve found my STA200 works best with a Schiit Sys., a combination MrDecibel mentioned in a thread a while back.  I don’t think I’ll ever sell this amp.  It just sounds too good when paired appropriately.