Magnepan 20.1 versus Infinity IRS Beta

If you are considering each option why wouldn't you also consider the new 20.7?
This is not an answer to your question and I don't think the new 20.7 will extend the bass further.
But it seems to me you (especially since you are at close to the same price point) that you might want to consider the 20.7 instead of the 20.1

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Because you don't mention the 20.7, price must be a concern. You can buy a set of Betas, if you can find them for around $5-6k and Maggies around $7-9k. I would suggest getting the Maggies and a pair of good subs. The Betas are great speakers, but they are also 24 years old. Parts and repair will be a hassle with the Betas. Going the Maggie/sub route will be more expensive, but I believe that route will be more practical...plus you will get excellent sound. You need a big room for the 20.1, you'll need a huge room for the Betas.
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I had owned since new a pair of Infinity RSIIa. (the next smaller EMIM equiped system from the Beta.)
I now own Magnepan 3.6

I would say either will allow really great mids and highs.
The Infinity will do bass better. If you want 'slam' them the Infinities will be better.
(IMO the upper range will be a tossup, the mids also, the Infinity will have a bigger discrepancy between the mids and lows than the maggies.

And I agree the Infinity are getting old. The biggest item are the EMIMs inner films, they are no longer available, and i sold a bunch of EMIMs for $200 EACH (I gutted my infinity speakers and made more money in parts than selling whole.)
Some company has (recently) made a replacement inner critical part for the EMIMs and EMITS. And if you get the Infinity, you should definitely get a full set of replacement inner foil parts for the EMIM and EMIT speakers.

Either set of speakers can really sound great.
I would say the Magnepan will offer a more seamless presentation. a better soundstage too. The Infinity will ROCK if you want that, in a way the Maggies never can

Tough call.

thanks a lot for your responses

I have a couple of Renaissance 90 which I loved until the day I heard with the same electronics and source I have, a Magnepan 1.7 .... yes a 1.7 !
no chance for my Renaissance 90 to compete with them in terms of high definition in the mids and highs ... amazing 1.7 !! ...
but anyway the Renaissance will stay where they are now

Quite a few years ago I falled in love in the system of a friend: Infinity RS1B ... as I have not the space for these monsters, I was wondering if the younger IRS Beta could offer a similar quality with a "Magnepan-like high definition"

but you are right in remembering me that the IRS Beta are becoming old ... which might bring some problems with it ...

I am hearing mostly big symphonic music and acoustic Jazz, so that I don't care so much about "slapping bass" but more on homogeneous bass-mid-highs integration, holographic sound staging, high definition and in hearing the space where the recording session(s) have been realized or if you prefer the ambiance sound...

one point where the 1,7 couldn't convince me completely was the color of violins which was slightly metallic and thin ... how is this with the 20,1 or 20,7 ?

I would be also interessed in the 20,7 but if I could get them at the US price ... I am based in Europe and the dealers here offer the 20,1 at a price above 22'000 $ us !!! ... most of the time without even the possibility to hear them !

thanks for your feedback