Nuforce STA200

Purchased one in April of ’17, for shits and giggles. Sold many of my " expensive " amps, because after a few months of this little guy breaking in, it bettered many of them. My only negative issue, because of it’s high gain, I do get a small amount of hum from my 104 db sensitive speakers, which was bothersome at some point. Hum is at constant level, does not increase with volume. Have not even done my AVM mod to it yet ( which I do to almost everything ). An amazing amplifier.

@erik_squires My understanding about the STA 200, is, it is a conventional AB design, taken from a circuit developed by Goldmund, also used in the Job 225. But yes, Nuforce ( Nuprime ) does use designs in other models in which you speak of.

Ordered a pair of Goldenjacks 10 db attenuators. Will see if it reduces the hum, without affecting the sonics ( doubtful ). If this does not work, might need to go back to passive ( never liked ), change to a lower gain preamp, or a different amp ( although I do like the STA 200 ). I gave up on tubes a while ago.

@aberyclark Thanks for the recommendation. I will try the attenuators when they arrive, and allow them break in time. Hopefully, they do not smear the sound much. If they do not work out, I will see what to do next. Thx. 

Has anyone tried a passive unit with the STA 200 ? ( @aberyclark , did you happen to listen to your Schiit sys direct, w/o preamp ? ). Thanks

I purchased a Luminous Audio Walker Mod, single ended, 3 in, 2 out remote unit about a month ago, and all I can say is, I will never use a preamp again. And, the STA 200 is amazing, and such a joy to listen through. Enjoy ! MrD.

jetter, I did try some 10db attenuators and did not like them. I also borrowed an inexpensive passive unit to go between my pre and amp. Did not like it either, with a 2'ndary volume control and an additional set of cables. Tried the cheap passive direct, and found it better in some ways to the preamp. So bit the bullet and am enjoying high end passive. I am glad, after a year, you bit the bullet, purchased, and are enjoying your STA200. Enjoy ! MrD. 

It opens up nicely with a superior power cord, especially over the stock cord. Enjoy ! MrD.

I have run my STA200 on several types of speakers, and it has had no problem running them to levels I am happy with. It runs slightly warm, and I leave it on 24 / 7, unless I am out of town overnight or longer. It has become my main amp for my Lascalas. Enjoy ! MrD.

As much as I like the Nuforce, I would not look for a speaker it can drive. I would pick the speaker, and find the suitable amp to drive it. This has always been my approach. Enjoy ! MrD.

Well, I just ordered another from Audio Advisor, as, I do not know how long these will be available. I wish I was excellent with words, because I would give this amp a tremendously positive review. It really possesses all of the great attributes of so many amplifiers I have owned, and have listened to, in all of my years. Is it perfect ? Are my ears perfect, or my speakers, or my room, or my sources, or my recordings ? No, But, it is just so musical and embracing, and allows me to enjoy all of my music. And, for the money ? Enjoy ! MrD.

I had a relatively high end tube preamp, which resulted in a hum through my 104 db efficient speakers, with this amp. The combo was fine with less efficient speakers. Same occurrence with a ss preamp, in both cases. Because of it’s high gain, it is a possibility noise can be a problem. The noise is not from the amp, as it is dead quiet. The other thing would be a very small amount of adjustment via the pre’s volume control. I love the amp though, and went passive. Some folks added a volume control ( a simple passive unit, something you said you did not want to do ) between their pre and the amp, to cut back the gain, and are quite happy. Enjoy ! MrD.

The STA 200 is not bridgeable, meaning you cannot combine both channels to make a single higher wattage amp ( usually impedance capability changes with the amp when you do this ). However, when you separate the crossover of the speaker, as you suggest, you can either horizontally biamp ( passively ), or vertically biamp ( again passively ), with 2 amps. Your example would be horizonal passive biamping. Each of 1 amps channels running the woofers, the other amps channels running the rest. Vertical ( which I prefer, based on my own listening ), would be each amplifier " dedicated " to 1 speaker, 1 channel to woofer, 1 channel to rest of speaker. This all works well when both stereo amps are the same. I hope this helps. Enjoy ! MrD.

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A purchaser of this amp, from early in 2017, stated " Conrad Johnson meets Krell ". I have owned a few CJ amps ( 2 tube, 2 ss ), and a few Krells ( but am familiar with many Krell amps ), and I have to say, this amp definitely has many " high end " characteristics. What I like about it, particularly, is how " tuneful " it is. With a better pc, it truly follows the bass and rhythm of whatever music I am listening to, and I cannot say many of my amps ( and believe me, there have been 100s ) have done so well in this area. The transients are fast, and the dynamics are incredible ( keep in mind my Lascala’s are quite dynamic ). The tone mimics the music, and the spatial presentation is high, wide and deep. A killer at $499., and of course, with the right loudspeakers. It is a very musical and enjoyable amplifier. Enjoy ! MrD.

The amp takes well to an upgraded power cord. Enjoy ! MrD.

Jetter, I believe you are speaking of the magnet ( ferrite choke ). Look up " what are the bumps at the end of computer cables ", as you will get your answer. These are sold everywhere, and have been for ages, in different sizes, by many manufacturers. Enjoy! MrD.

I feel a little embarrassed to ask this question, and I will explain why. Simply, in my 50 plus years at this ( as an audio professional and consumer / hobbyist ), I have opened every amp I have every owned, to do a mod or 2 of some kind ( everything can be modded, for improved sq ). Has anyone been under the hood of the STA 200, as I have a few mods I would like to do. Removing the 4 philips screws from the rear side walls, I would think you spread the side walls, from the rear where the screws were removed, to loosen the top. I have tried, very gently, but they did not budge. I did not want to use excessive force. Nuforce has not answered my emails, as I suppose they do not want me in there. I would appreciate any response. BTW, as I have said before, this amp does so much right, musically, that although some amps might be better in 1 or 2 ways ( through a particular set of speakers, due to efficiency / impedance ), this little amp is quite the beast. I have owned AR, Krell, CJ, Threshold, Bedini, Ampzilla, you name it. Amp sounds best on a non resonant shelf, being left on continuously with signal playing through it ( a few hundred hours ), an after market power cord, and a 1-2 lb weight on the top center ( I use a thinking man statue over a padded piece of 4 in. X 4 in. piece of granite. Enjoy ! and Happy Holidays. MrD.

The Saga and STA 200 work well together. The input gain on the amp will easily allow you to use the Saga in passive mode, which I prefer over the tube stage. It is of course personal, and you might like the added color and roundness of the tube sound. Note : It also has to do with your source's voltage output and power supply design, when using it in passive mode. Enjoy ! MrD.

I have a modified Adcom GDA 700 ( an oldie ) along with an after market cord and fuse. I've tried some more recent units ( all under 1K retail ) and still enjoy mine. I have an AA DDE V3.0, with an upgraded power supply and power cord in another system, which I also enjoy. Enjoy ! MrD,.

brad, if you were to connect the Nuforce to your speakers, without connecting anything to the amps input, ( any amp for that matter ), you may find the Nuforce / other amps to be quiet through the speakers. I have done that with both of my Nuforce amps through my 104 db efficient speakers. The Nuforce amps were silent.I believe you may have a problem with the Freya, or a tube ( s ), as others have not reported very loud hum / static / hiss etc. Enjoy ! MrD.

OK

Brad, does it run cool on the speakers currently being driven with the Proceed ? It is AB for sure. As a correction, if I may. The STA 200 does not use the same circuit " board " as the Job, but it does share the same circuit design. The design is exclusively Goldmund. There is a lot of fascinating information about this circuit on the web, licensing agreements, and differences between the Job and the STA 200, and much more. Enjoy ! MrD.

If anyone thinks, or feels ( jeenam ) that the circuit boards are identical, I would like to see proof from you, or anything in writing indicating they are identical. They might be similar, but are not the same. If you look closely at photos of each ( there are many photos available on the net ), you will notice differences in the board " traces " of each. You can easily see these differences in the 2 photos provided in the link. I would like to move on from this. Merry Christmas to all. Enjoy ! MrD.

The poster of the blown amp might be a competitor ( or owns a competitors amp ) at or near the $499 price. You never know. I do know a few individuals who returned the STA 200 because it did not work in their system, but the majority of people who private message me are very happy, as some others here. BTW, it is a great little amp when used properly. However, I am currently rotating amps ( again ), as I will be cleaning out another closet full of amplifiers. When this started a few years ago, I had over 100 amplifiers in my collection. Just saying. Happy New Year to all. Enjoy ! MrD.

Hi again all. Japol, if this shhhh sound is audible from your listening chair, again without anything connected to the amp’s input, through your speakers, I would not worry about it, although I understand the concern. Some of my other amps, specifically high wattage amps ( 200 + wpc ), do have a hiss, but not audible from my listening seat, under the same conditions. My experience with, not only high gain audio equipment, but " wide bandwidth " equipment ( Spectral as a good example ) might be prone to spurious noises from things such as digital gear, certain lights / switches, some kitchen appliances ( refrigerators and microwaves ) and even dirty electrical and nearby wires, might create this shhhh you are hearing. Do you have another amp you can try this with ( other than the STA200 ) ? Are you using the supplied power cord with the STA ? Try plugging the amp into another outlet, even if it means using a power strip, or extension cord, and see ( hear, lol ) if the Shhhh gets lower. Your speaker cable can also be acting as an antenna. Keep the speaker cables away from any electrical cables, and if you cannot, do not run them parallel with one another, if possible. Don’t give up, we are all here to help. Enjoy ! MrD.

With either of my STA 200s connected to my Lascalas, at 104 db efficiency ( no input connected to amps ), they are dead quiet, as I hear no hiss or hum ( of course, the amps are on ). I did have issues with hum through a few preamps I owned ( own ), and now own a top model Luminous Axiom Walker unit, without problems. Unless the amp is defective in some way, I believe it is simply amplifying any  noise preceding it. Enjoy ! MrD. At this time I am using the amp pair to vertically biamp ( passively ) Signet SL 280ex speakers I have set up in another room, and the system is excellent, without any hiss or hum, using a DoukAudio passive preamp, hifi version, which I have found to be cleaner than the Schiit sys ( $40. or so from the Bay ). Currently rotating amps for the purpose of selling many of them. Enjoy ! MrD.

Checking in. Japol, how are things going ? Hello to everyone else. Enjoy  MrD.

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.

Removed my last post because it was about another amplifier, rather than the STA 200. Sorry for not keeping the thread on track. Enjoy ! MrD.

To both jetter and abery ( and anyone else ). Although I am not using my pair of STA 200s in my main system, I do believe it is an amazing little amplifier. I also believe I have as much, if not more, experience than most, in using the amp with several different combinations since my acquisition of the first sample almost 2 years ago. The amp was designed with a passive pre to go before it, and for a year now, this is how I have been listening. Not just with the STA 200, but with other amplifiers. Without naming names, I owned 2 top tier preamps, that were quite excellent, but ultimately, determined they were coloring, and robbing my system of details in the music. I would suggest both of you to take your preamps out of your systems, and run only through the SYS, for about a week. There will be an adjustment your ears will make, as I know you will not like everything you hear at first. But if you really appreciate your recordings for what they truly are, and can be, given time, you, like me, will stay passive. This is especially true with the input sensitivity, and gain, of the STA 200. No preamp, one less pair of interconnect, and I am telling you, your preamps are not needed. My Luminous unit is incredible. Silent, reliable, and offers me remote volume, which I never had before in my main 2 channel system. My Dac is quite amazing as well, and it is an older type ( modified Adcom GDA 700 ), and drives any of my amplifiers with ease. And if I am wrong, after about a week, all you need to do is go back to your preamps with an extra set of interconnects, and, enjoy ! So, there you have it. Enjoy ! MrD.

The first thing to do would connect the Sys, direct, play music of all types that you often listen to ( I do say give it about a weeks time ), and determine if you like it, better, or not. My Luminous ( $1250 ) is quite a bit " cleaner " than the Sys, but, it should still give you more of a sense of " straight wire ". Passive is not new, but sources have gotten better and beefier in the output stages. Just give it a try, be patient, and see if your ears are good with it. If you like it, then, you can shop for a unit that has what you want and need. Again, if you don't, well, now you know. Enjoy ! MrD.

If anyone is interested ( and this applies to anything ), you can open up, go inside of the sys, and Dynamat the circuit board and some of the chassis, as you will hear a significant improvement in detail and resolution. It will also add some weight to the chassis. Always need to be careful when pressing down on the boards, as you do not want to break the " traces " ( Sorry, been doing these mods for 50 years, and they work well ).

So, has anyone new tried passive ? Even with a Parasound A21, as it works with amps that have normal gain.

dengief, welcome.....I am not sure what Mr. V is indicating....I am running my pair of STA 200s in a vertical biamp situation ( something I have been recommending for a while now, given having two identical stereo amps, or of the same, 4 monoblocs ), and I am having no issues to speak of. The speakers I am using are a pair of Signet floor standing towers ( I was a rep when I got them ), and they sound very good being driven this way, and of course, with the NF amplifiers. I have used professional Yamaha amps, Hafler amps, Citation amps, and some others ( I had a s---load of power amps at one time ), with the same configuration, with excellent results. I owned 2c’s, and later 2ci’s ( in the past ), and have had clients with them, and never an issue, and vertically biamped them, too. Unless Mr. V. is doing something different with the latest incarnation of the model 2s, I do not see a problem. I have always preferred, is sq, vertical biamping vs horizontal, and I have done so with Martin Logan, B&W, Kef, Klipsch, Legacy, and others, that had the passive biamp ability, without issues. I would encourage you to read the manual of the Vandys. I hope this helps, but if it does not, I do understand.....my best, and Enjoy ! MrD.

The NF STA 200 has a much wider bandwidth than the Rotels. What this means, I am not really sure, technically, because musically, the high frequencies on the NF are musically capable of reproducing much higher frequencies, with music signals. I still do not know what he has done differently, than 10 years ago. There must have been some folks ( likely just a handfull ), who had some issues, as it only takes one issue to raise a white flag. Same happened many years ago with a particular speaker wire, by Polk, that caused some amps to oscillate. I had these cables, and never experienced an issue. I know the STA 200 does not do well below 4 ohms, but this oscillation thing is completely different. If it were me, I would try it, as I have had very good luck, without things oscillating during my many audio years. But, this is me..........you can always replace tweeters, lol.....Seriously, I feel the STA200, based on all of the circuit research I did, would not go into oscillatio; The Vandys, as much experience I have had with them, never caused a problem to any amp I am aware of, except for a clipping issue, which is different than oscillation. It is your call. Could create a new purchase of a pair of tweeters. The Nuforce will likely be better, in sq, than the older Rotels. Like I said, if it were me......You, are not me....Enjoy ! MrD.

Thank you for the feedback. What changed your mind about trying them this way, except time ? 

I encourage you to leave everything on, 24 / 7, with music playing through the system. It will take, ime, a few hundred hours, for them ( the preamp, too ), for things to gel ( lean bass, as an example ). They should be better, in sq, over the Rotels, in every area, but with a new preamp, you might not attribute all of these changes to the amps themselves.......And yes, they are very quiet....Anyone who experienced them to be noisy, was experiencing the high gain of them, amplifying noise earlier on, in the signal chain. Thank you for the feedback.....Enjoy ! MrD.

A couple hundred hours for break in. Leave it on, continuously, with music playing through it, if possible. The question of vertical bi-amp....I feel it is significant, but this goes with many dual amps I have had experience with. As far as a purchase, making any percentage of improvement, well, this is all part of our industry. It is a great amp, at the selling price, for many systems, and not the best, for others. System matching is still very important. 

Well, I have been rotating amps in my collection, to determine which I should sell, and which to keep. I am still amazed, listening with the Nuforce STA 200 in my system. I cannot complain about it, tear it apart, want for anything. It does not have a house sound, and best, it gives an impression of the best of tubes and ss, in my system. Because I use a passive pre, it is extremely synergistic with the rest of my system, and simply works. It allows me to enjoy listening, which it is all about. It has been in my system for a month now, and I am doing fine. My best to all !. MrD.