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I'm looking for a no-fuss SS amp to replace my dead Audio Research SD135, between my Audio Research LS 27 line stage and Vandersteen Treo speakers.

A Nakamichi PA-7A II caught my eye.  My tech recommended it because it has a lot of energy storage with refinement.  It's a Stasis design with  zero global feedback and 132,000 uF.

Unfortunately, this amp is rare enough that most opinions are not based on listening.  I thought the PA-7A II might be a good bet because I'm really enjoying its little brother, a 75 wpc Nakamichi TA-3A Stasis receiver.  In fact, I like it better than my old Audio Research D130 power amp (although I wish the little Nak had more power).

 

Are zero feedback and high energy storage important for a SS amp with the Treos?  What would you look for in an amp for the Treos?

 

Thanks!

 

 

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Davo, 

I have owned 5A and 7A before with my 1cs and 2Ces. I wouldn’t say that they are sonically ideal for Vandersteens especially after hearing Mccormack’s and Ayre’s but if it’s temporary then they will suffice. They are great amps but I find that the price that they usually come up for on used market is usually reflecting the rarity and not the capability. There are other Thresholds and Pass Labs amps that sound similar and are newer and cheaper. Not to mention with age you are looking at some work to really make them perform at a level that the Treo’s deserve.

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Davi, I owned a Nakamichi PA-5A II (and matching preamp) that I ran with 1Bs and 2ce. I know it’s not the same as the more powerful 7A, but likely is similar. I would pass based on my experience, the age, and how far amps have come. After researching good matches - Ayre, McCormack DNA, etc., I picked up a Belles 150a. It was good for the price (around $500) Have since moved through 3a sigs and own quatros. My big amp “Ah Ha” moment was when I put a Belles 150a Reference V2 (around $1,400 used) in my system. I’d say it has a lot of the impact and presence that I get from my current amp, an Aesthetix Atlas. It far surpassed the Nakamichi I had. For likely a lower price than the Nak, I’d put the Belles 150a Ref V2 high on your watchlist. Let us know what you decide!

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Davo, I concur with Stratocaster.  I had the 7A with my 2C’s back in the 80s.  Way to long ado to share any specifics regarding the sonics, but for the money, I believe there are better choices. 
Ive never owned any of Nelson Pass’ products, but they are highly regarded.  Rogue amps also seem favorable among some members of this forum. 

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@davo,

I started with McCormack amps upgraded by SMcAudio, but lucked into a pair of Ayre MX-R monoblocks (non-Twenty), and I haven't looked back. I ended up finding a KX-R to make a set, and find it to be the end of my search.

I also run my Treo ( non-CT), with Atmasphere MA-1/MP-1 for the winter months, as I finally have the funds to indulge in a SS/Tube system.

Which do I like best?- I like both.

I would love to compare Pass and Ayre, but am waiting for a M5 to come up on the used market.😊.

Bob

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Wow! Thanks for all the great tips. 

So far, the consensus seems to be that there are better alternatives at this price than the Nakamichi Stasis amps.  Mentioned so far: McCormack, Ayre, Threshold, Pass Labs, Belles, Aesthetix.  Of those, SS amps at about the price of the Nakamichi ($1300) seem limited to perhaps Belles, or possibly McCormack, if I could find one.  I did find expired ads for Belles on hifishark in this range, and that gives me hope.  The reviews seemed positive, and the review I found of the 150a Reference V2 was positively glowing.

My tech made dismissive comments about certain amps with low internal energy storage.  For example, he thinks the 36,000 uF in the Ayre V-5xe a joke, compared to the 132,000 uF of the Nakamichi.  My concern would be a potential loss of resolution in loud, complex symphonies, and a lack of large-scale dynamics.  Is that really a concern with the Treos?  Perhaps raw capacitance isn't that important.  Are there any specs you would consider important?  I did notice that Richard Vandersteen recommends zero feedback amps.

I read that the Belles is not a zero feedback design.  Anyone know how much feedback is used?  I believe the Stasis amps are zero global feedback.  My ARC SD135 was 7 dB, while my D130 is 21 dB.  I don't know whether this is coincidence, but I'm really surprised that I'm not enjoying the D130 as much as I used to.  It doesn't sound that good to me.  The Nak receiver sounds better to me.  Does that surprise any of you?

I'm intrigued by Nelson Pass designs, but I don't see much chance of finding something there for under $2000.  

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I realize that there are lots of opinions, and some people have an axe to grind.  Others may be much more concerned with technical arguments than listening, and even folks who listen may be listening for other qualities than I do.  That said, here is an analysis given to me of what it takes to drive the Treos well.  It comes from someone whose technical competence I trust, but who might not have much experience with these speakers.  Do you think his arguments make sense?  If not, how would you counter them?  Thanks!

Looking at pics & measurements of the Treos, you've got two issues to consider for amp choice- 1)Very low efficiency, saved somewhat by impedance staying above 6 ohms through audio range, and 2)Bizarrely mass-loaded low bass driver.  This means the amp needs not necessarily to be really high power, but does need to have copious & fast current delivery, meaning high current output devices with lots of stored power supply energy instantly available to them, i.e., bigass supply capacitors located as close as physically possible to output devices.  But you also need lots of finesse on top to prevent exciting potentially harsh resonances in that tweeter.  This is a tall order.

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Just saw this post.  Vandy's sound best with a fully dual differential balanced amp that has zero global feedback.  I have been running only the Ayre integrated amps with my Treo's and Quatro's.  They only reason I'm about to sell the AX5/20 is because I now have Richards's mono amps.  Ayre is a great match for the speakers.  They are clean, uber low noise floor and fast.  They aren't 'warm', but they are so good that you realize over time that they are more accurate than most amps/integrated amps under 20k or so.  This is just my opinion, but it's a great match.  

One of the dealers I know sells Sim Moon amps and feels that they are also a great match.  I do like some of their new amps.  Never heard them on Vandy's.

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Thanks ctsooner!  You mention "fully dual differential balanced amp".  Is that an advantage for Ayre over Belles?  Looks like the Belle amps don't have balanced connections.  My ARC LS 27 line stage does...

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Davo,

If your average listening is at levels louder than normal then you will certainly have to look at spending a little more and getting something that has a lot of power reserves. Guess if you stretch your budget a little then you might be able to have some choices that might be worth it in the long term. On the other hand I saw a PA7 under a grand on Audiogon that can help answer your curiosity around zero feedback amps combined with Treo’s. If you don’t have a specific sonic signature that you are looking for then it won’t matter how the combination sounds. In the worst case you can always sell the amp (although I have my doubts about their popularity). 
 

What part of the US are you located at? If you are in SoCal I can lend you a Mccormack if you would like to try it out.

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stratocaster- You are kind.  I am about 1000 mi North of you.  Question: which McCormack do you have, and have you had Steve rebuild it?  To the argument that Treos benefit from lots of energy storage placed as close as possible to the output devices, McCormack's DNA approach might be really smart.

Looks like the PA7 you saw just sold (both of them). 

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I'm looking now at ads for used Nakamichi PA-7A II, Belles SA-100, and (just missed) an Ayre V-5xe.  What do you suppose would the pros / cons of these with Vandersteen Treos (and ARC LS 27 preamp)?

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The Ayre V-5xe is a popular and well established match under $3k. I do not have experience with it, but imagine you would likely be very happy with it. The only negative I found on it when researching amps is that it may be a little light in bass impact. You may enjoy searching Audiogon forum posts by member Bigtee. He compared this Ayre with a number of different amps. I saw that SA-100 also. It is still listed on us audio mart for sale. 

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1 hour ago, davo said:

Question: which McCormack do you have, and have you had Steve rebuild it?  

Davo,

I have the DNA’s .5 and 1. Using them with the 1C and 2CEs, the sound is the same. The .5-1C combination makes you feel that the amp and the speakers are two peas in a pod. The DNA1 is paired with the 2CE but since my listening level is moderate and not that high I am barely pushing it.

Boh amps are stock and am in the process of upgrading them. I am not certain if the upgrade will enhance the sound so much as to justify the cost but only time will tell.

If you are up for it then there’s a guy in Tuscon who is selling a Mccormack DNA2. It’s the big Kahuna of amps and a beast at over 100lbs..That will drive not only your Treo’s but every speaker in your neighborhood if they are connected.. am sure you can work out some arrangement to get it shipped..

Edited by stratocaster
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@stratocaster, All.

SMcAudio will upgrade all McCormack product. As they pretty much toss all the innards, you can buy a non-working model to have upgraded.

Pat/Steve upgraded a pair of DNA-1's doe me, for monoblock performance.  I wish I could tell you how they sounded, but Steve changed the impedance to something like 5K, so I couldn't use my High pass filters (balanced). So, I then waited for some RCA high passes to come to the used market. Whilst waiting, I then scored a set of Ayre MX-R's, and the DNA-1's languished until I finally sold them. Albeit at a loss😢, but the Ayre is a keeper.

@davo,

It all comes down to budget and how serious you are with your music.

Belles is a great pairing with Vandersteen if you are on a tight budget.

I use Belles in my office system.

But, the Ayre takes it a step further, of course, at a cost.:classic_angry:

Bob

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You folks are great.  I'm finding this very helpful!  I still have the impulse to grab that Nakamichi, partly because I like what the little one is doing with piano and trumpet sounds, and probably partly because I drooled over that amp when I was a starving grad student.  But the Ayre V-5xe seems the best bet in the long run.  

I actually first heard the Treos in a system with ARC LS 27 and Ayre V-5.  Fantastic!  At the time, I had ARC LS17 and D130, into Vandersteen 2Ce Signature.  There was something about the sound in the system with the Treos that seemed so real, almost holographic.  I was listening to a CD of The Bay Brass, playing Lauridsen's "O Magnum Mysterium", and the brass quintet sounded like they were in the room. That eventually led me to the LS 27 line stage, which I'm happy with.  And the D130 gave way to my broken SD135.  I may be coming full-circle.

Out of curiosity, where do you think the ARC D130 and SD135 fit in this line-up?  

 

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I really wanted SS as well when I first got the Treo's.  I sold my tube preamp and mono blocks for an Ayre integrated amp.  I was very happy I did, but when I upgraded to teh Ayre AX5/20, it was a WORLD of difference.  It's in a different league, but they are selling for 6800.  Not sure what your budget is.

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@ctsooner-  Very nice!  I have seen a used V-5xe at prices I think I can manage, but that's about the limit of my budget.  I just looked at Art Dudley's review of your amp: "You are going to freak out."  :-)

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Davo, the V-5xe is a GREAT choice in the 2500 range.   You have a GREAT preamp!  Adding the V5 is a nice pairing.  If you sold your LS 27, you'd probably get at least 4500 for it based on what sales have been.  They also move very quickly from what I've seen.  You'd be looking at 6500-7000 for an integrated and that allows you to upgrade to the AX5/20 that is going to sound better as the amp section is the diamond version of the V5 and the preamp in the Ayre is one of the most transparent you can get as it's closer to the preamp in the KXR than the KX5, because of the way it's integrated.  

If you want to stay with separates, you can't go wrong with the Ayre amp.

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@ctsooner  Oh, oh.  Now you've done it.  I have to put on my thinking cap!  Thanks for the suggestion.  This would mean replacing the LS 27 / <power amp here> with the integrated Ayre.  Hmmmm.

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Not in the same league. Not even close to my ears. I will say that once Ayre went to the diamond circuit that Charlie Hansen drew up while in college , but didn’t incorporate until the 20th anniversary (naming the products with the 20 designation) that they took it to another level. 
 

Non 20 designates amps are still in a different class to me than the Belles. Only my opinion though. 

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