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Atma-Sphere MA2 Mk2.3 / Krell KSA 250 / Passlabs?

Good Evening Fellow Audio Heads!

I'm upgrading my amps (will be a big step up from my NAD S200) which I still love dearly.

The amps that I have the choice to purchase second hand are:

Atma-Sphere MA2 Mk2.3 - AUD $9000
Pass Labs X250.5 = AUD $6995
Krell KSA 250 = AUD $3000

Now the Krell and Atma-Sphere are class A. The Pass labs A/B. Front End will be a Atma-Sphere MP1 Mk3. Speakers are the unfriendly Dynaudio Confidence 5 (no intention of changing these lovely speakers)

Can you please advise your thoughts on what amp would sound best in this situation. Music Reggae / soul / female vocals. What amp listed is the best value? I would say either the Atma-Sphere or the Krell. I have only heard the Pass-Labs in person and that sounded nice and smooth. I like detail in my music.

Many thanks for all your help as it's impossible to do A/B comparisons.

Cheers
Che
che13
rwjp
33 posts
 
What makes the MA2 able to handle larger impedance swings than the M-60 can handle, and how can a consumer evaluate this?

More tubes= lower output impedance
m-60 4.1 ohms
ma2 1.75 ohms.

would be my guess.
Post removed 
mapman's avatar
mapman
22,627 posts
 
How does the # of tubes affect the ability to match the impedance curve?

If it can drive the big Dynaudios I'm thinking it could also drive larger Ohms. I have not heard where there is a tube amp out there that is a good fit prior though.
rushton's avatar
rushton
2,445 posts
 
As Ralph has explained it to me (and I'm paraphrasing), the greater number of tubes in the MA-2 lowers the output impedance of the amp relative to an MA-1 or an M-60 (see Rwjp' post above). This lower output impedance allows the MA-2 to drive more easily a broader range of speakers (i.e., be less speaker sensitive) than many other OTLs.

One still needs to be cautious about the speaker's MINIMUM impedance (e.g., probably not less than the mid-3 ohms range) and still to seek speakers that have reasonably smooth impedance curves (no steep drops or spikes) without a lot of crazy phase shifts going on.

Ralph maintains the MA-2 can drive most speakers on the market, but there will always be some designs that simply won't be a good match. So, best to check.
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audiofeil
4,011 posts
 
>>How does the # of tubes affect the ability to match the impedance curve?<<

OTL amplifiers have no output transformer.
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