This is a very special amp from Clayton Audio. Wilson Shen just let this unit off of his bench and it has some extras not available on his already excellent stock S40. As he noted, " The S40 use a pair of 41,000 uF x 2 for primary power supply bank and 2 pairs of 3,300 uF x 4 for 2nd power supply bank. I will replace them by a pair of 1000,000 uF x2 for the primary bank and 2 pairs 4,700 uF x 4 for the 2nd. these are now we use in M200." This S40 puts out 50 watts of class A power into 8ohms, and does better than doubling that down to 4 and better than doubling again to 2 ohms. So you are getting an S40 with a greatly enhanced power supply. The evidence was proven when we put these on our 3 OHM reference speakers from Boenicke Audio. We've never experience this kind of bass from that speaker. The power supply in the S40 tells the tale. It just plays music as it happens in a live setting. Amazing for the cost of these speakers. If this model were available as a regular product from Clayton, you could expect to pay $6000.
This unit just came off of Wilson's bench in January. If you want a pinnacle of class A musicality in a solid state design, then this is the amp for you. One caveat, this amp, like other Clayton amps, has a slight operational hum that is not discernible during playback, but can be heard if you place your ear next to the unit without playback. If this is of import to you, this is not your type of amp. If tremendous bass, sound staging and mid range presence are important to you...look no further. Lastly, this amp would be an ideal match for any speakers that dip in impedance...this thing will play down to a short.
Here's what Positive Feedback had to say about the stock S-40; "The Clayton S40 really lets the music shine through. It is enchanting and neutral, but not lean. Precise and accurate, it glows with rich textures, and has bass to die for. I can't imagine a better sounding solid-state amplifier.
This could be the amp of your dreams when mated with the right speaker. $4,500 is an absolute bargain to get this kind of performance. Properly matched, the S40 could take you to audio paradise and keep you there.
Is the Clayton S40 that good? Yes, it is. My highest recommendation.
Get yourself to a Clayton dealer and prepare to be seduced."