Nuforce STA200

Hi Mr. D,

I apologize for not getting back to y'all earlier. I got caught up with some other stuff and just decided to order a Schiit SYS to see if that fixed the problem.

I was using a cheap FX Audio Tube pre-amp/buffer with the upgraded GE tubes. The tubes definitely produced a significant amount of noise once the volume knob hits the 9 o'clock mark, and the noise only increases from there on. I received my SYS yesterday and tried it out last night. With my chromecast audio and NEC cd player connected on the SYS, the noise on the speakers was cut down in maybe half. There is still a very faint shhh noise on the left speaker when I put my ear right next to the drivers, while the right speaker has a faint high pitched noise on top of the shhh noise. I'm only a beginner in audio stuff, so I would assume this would be what you call the noise floor of the amp, right? Now with the SYS, music is more detailed and has a very slightly wider soundstage compared to the FX Audio tube preamp. I tried connecting the chromecast audio to the FX Audio then routed the sound to the SYS before going into the amp, and the sound warmed up a tiny bit with a very minimal sacrifice in soundstage. So, based on the different combinations that I've done so far, the noise that I'm hearing is coming from, or caused by, the amp itself.

Last week, before ordering the SYS, I tried the amp plus FX Audio tube preamp on my daily system with NHT speakers. There was still that shhh noise and a slight high pitched noise (I don't exactly know the frequency of the noises). Although the noises that I'm hearing on my NHT's with the amp are similar to the noises that I'm hearing from my Pioneer stereo receivers and vintage integrated amps. I guess the noise floor is normal with such a high gain amp. Kindly correct me if I'm wrong.

Based on last night's listening session, I am happy with the amp. I will give it another go tonight to see if my thoughts change. Before getting this NuForce amp I had a Linn LK140 that I bought used, but decided to return it to seller because one channel was buzzing and when I opened it up there were signs of damage, repair, and a missing capacitor. That amp was quiet though, aside from the buzzing on one channel. My other amp option is to get another used Linn amp and hope I'd get lucky with a good example.

Thanks for your help, Mr. D, and to everyone on this forum! I really appreciate it.

Hi Japol, I hope Mr. D posts here quick to help you out as I don’t have enough experience with gain issues, so these are just random thoughts until the voice of experience chimes in. My first thought would be that to determine if you have a gain issue you should just hook up the Sys with the amp, and the amp to your speakers and with no sources connected see if there is a "hiss" caused by too much gain or the if there is still the "high pitched noise". If not, I would think, but may be corrected, that the noise issue is being generated by your sources, wiring or a ground loop.

If you determine that in fact these noises are the result of the amp I would not think twice of exchanging it for another one or if you choose a refund. If it was a noise floor thing I would think the "hiss" would be the same level from both speakers, and no matter what there should be no "high pitched noise". But again, wait for Mr. D.

Hey Jetter, Japol and all you other audio gents. Japol, if your STA is causing a hiss through your speakers, without anything connected to the amp's inputs, I would say this is not normal. Either the amp is defective, and / or, the amp, or the speaker wire, is picking up stray electrical noises from somewhere ( see my earlier post ). If you like the amp, I might suggest you contact the seller and arrange for a replacement. If the replacement does the same as the 1st, I would assume the amp does not work in your environment ( again, the sensitivity and gain situations ). Keep in mind, things such as under cabinet kitchen lights, ceiling fans with remotes, florescent bulbs, and many other things, can be picked up by amplifiers, which could be the situation. Did you try your other set of speakers ? Keep us posted. Always, and Enjoy ! MrD.

The Nuforce should be dead quiet with Just the sys. When I had my RP-5 in for warranty work, I used my Pro-Ject s2 Pre Dac as a preamp. Dead quiet. I mean dead quiet!!! My Zu's are rated at 101 db. Slight tube hiss is normal (ear against speaker) for the rp-5. The Nuforce has such high gain, along with my efficient speakers, I needed the SYS between the pre and amp to pull things back. 

Hi Mr. D, jetter, and aberyclark, and everybody on here! So tonight I went ahead and did an experiment. I bought a grounding adapter to isolate (disconnect) the ground from the 3 prong plug from Lowe's. That did not eliminate the problem. I also tried plugging in the amp straight to the wall outlet, but still the same problem. So, I went ahead and used a different speaker wire... problem still there. Then, I tried using my Sony TA-F500es just to see if it produced similar hum/hiss... they're still present but it is more quiet compared to the nuforce. Now, I'm not sure what's wrong with my system. 

I also tried connecting my nuforce to my NHT floorstanders and the noise is present, only louder. 

All these tests were with the sys connected to the nuforce, except the test with the Sony integrated. The hum is isolated to the mid-range driver and the hiss (sounds less of a hiss and sounds more like electricity buzzing) is isolated to the tweeter. I tried recording the noises on my phone but it is difficult to be discerned from ambient noise. 

I feel like I can live with the hum and hiss/buzz, but I also wouldn't want to be keeping a defective amp. Tough call.

Thanks again, guys!