Comments on Bryston or Krell for Dyn Temptations

I am currently driving a pair of Dyn Temptation speakers with a Parasound A21 amp and ARC Anniversary pre-amp. Would like to make a big upgrade to Amp, and would like comments on the Krell Evo 900e and Bryston 28BSST2 amplifiers. Looking at mono amplifiers, and have read great things about both the Krell and Bryston monos for both clarity and bass extension and resolution. I have read enough to conclude that higher power amps would be a proper step. Any other thoughts on power would also be welcome.
My opinion is that a high powered amp on an efficient (91 db.) speaker like the Temptations is a bad idea unless you like to play your music super-loud. The Temptation is a superb speaker that deserves the very best amplifier you can afford. "Best", however, does not mean "most powerful".

First, almost all high-powered amplifiers use a lot of negative global feedback to stabilize the circuit, and negative feedback, in most amps, makes them sound unnatural and uninvolving compared to an amp that does not use global feedback. The Ayre monoblocks, which put out about 300 watts per channel, and the darTZeel, which puts out about 150 watts per channel, are both examples of "no negative feedback" amps that sound superb. Rowland's Model 625 amp uses no feedback and even Audio Research now makes a no global feedback amp. With a really good speaker like the Temptations, you can plainly hear the difference.

Second, high-powered amps use a lot of output transistors or output tubes, which also generally makes an amp sound worse. When a lot of output devices are paralleled, the sound becomes unclear. Each output device amplifies only a part of the music and the signal might not arrive at the exact same time from all of the transistors, even if they used matched transistors. Two or three pairs can give good sound, but with more than that, it is quite difficult to do. The best sound is with one pair, and the best example is the darTZeel, which uses only one pair of transistors per channel.

In conclusion, as long as your speakers are efficient, a lower powered amp, especially the elite amps that use no global feedback, will generally sound better unless you like to listen really loud or unless you have a huge listening room that is hard to fill with sound. With a great speaker like the Temptations, quality is better than quantity.
Thanks so much for taking the time for such a detailed and inciteful response.

Two things -- I do enjoy playing music very loud at times. For some music, such as feeling all and especially the base pedal notes on a good recording of Bach's Tocatta and Fuge in D Minor, emotion sometimes overrides my good judgement on the volume control. This loud playing is more the exception rather than the rule, though. Second, I do not have an issue with the music filling up the room with my current amplification. I am looking to upgrade in an effort to improve the sound quality and hopefully improve the sound stage by obtaining a higher quality amp as well as the advantages afforded by monoblocks.

I must certainly audition the Ayre monoblocks, and hopefully compare to, let's say, a Krell amp. I unfortunately live in a fairly small coastal town, but I will make every effort to get a proper comparison to hear what you have explained so eloquently above (not always easy without my travel to another city). I agree that the Dyn Temptations are very revealing, and one thing I enjoy over and over in my listening, is to hear the cross melodies of the various parts of a symphony orchestra.

Thanks for your persective. I do happen to err on the side of excess, but will definitely take my time to make the correct amp selection.

I am drawn to all items that claim "it allows the music through" without coloring or altering the original sound. I am guessing from your comments that the zero feedback accomplishes this.
Symphonic music is the most demanding type of music for an amplifier, requiring the most power, but the Ayre and darTZeel amplifiers I discussed are both sufficiently powerful for the Temptations provided that your listening room is not really big - both amps have excellent power supplies and have no problems with symphonic peaks.

In any event, you should be focusing on what is going to sound best MOST OF THE TIME - if 95% of your listening is at normal volumes, then you should focus on quality. In addition to darTZeel and Ayre, you should consider top quality tubes amps that are zero-feedback, Class A-biased triode designs. I also really respect and like the CAT amps - they use a few decibels of global feedback and it is difficult to find the right tubes for them, but they nonetheless sound superb and are enormously powerful.

Good luck.
Thanks again for your comments. I'm sure I will enjoy the journey of selecting and purchasing new amplifiers, and in the meantime enjoy the music with my Dyn/ Parasound/ ARC combination. I'm definitely not suffering with this set up right now.

My room is definitely not too big. The Parasound A21 provides plenty of power. Don't think I have ever reached the limit of the amp at this point, so have no concern over your recommended amps driving the Dyns to both normal levels or above normal levels. Absolutely agree with finding the best sound at my normal listening levels.
also consider the Hegel H-30; reviews will be forthcoming; its a brute of an amp; without the feedback issues; and should be considered in the same category. i have Bryston 28sst's; and really enjoy them on my 87db Venture speakers...great control; fantastic base; great sound stage and noise; or choked sound..have not heard your Dyn speakers... don't forget the 20 year warranty and great reliability of Bryston;and synergy with preamp is also important...sounds like you will notice a nice improvement regardless of which path you choose. Good luck; let us know.
Thanks, Mribob. I have never heard of the Hegels so did some reading. Will be interesting as reviews get published for the Hegels. Will definitely keep an eye and ear out. Thanks for the comments on the Brystons. I have the Bryston CD player and absolutely love it. Glad to hear you are enjoying these with your system. Interesting I don't see too many of the big Bryston's for resale, so I bet others are enjoying just as you are. I agree that I am trying to transition from really good to better. While I enjoy tweaking and upgrading, I love listening.