Pass Labs Xa 100.8 vs Agostino Progression Monoblocks

alfa100

Well-Known Member
Aug 29, 2014
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South Africa
I have the opportunity to trade in my Pass Labs Xa 100.8 to a Preowned Agostino
Progression monoblocks (First edition) I have Wilson Sasha speakers. Opinion needed .
 

bryans

VIP/Donor
Dec 26, 2017
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You could have them shipped to you for a home demo. I would think the dealer would do this if you paid for shipping. Sure it will cost you money but better safe than sorry. Hey the dealer might even cut you a deal on shipping if you decide to keep the amps.
 

Alpha121

Well-Known Member
Aug 15, 2020
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So, I think this is sort of an apples and oranges comparison. The two amps will sound very different.

Your speakers present a very challenging load in the bass region, with both low impedance and the electrical phase angle. There is little doubt that your XA100.8s are currently running out of steam there. Take a look even at the other Pass Class A amp reviews and tests, you will see that even the XA200.8s are not the last word in bass control and drive with a challenging speaker like the Sasha.

However, the mids and highs with the Pass are to die for, in the view of some (me included). What you ultimately give up is bass control and slam, again when driving a challenging speaker like the Sasha. Or, my own Focal Scala Utopia Evo.

If you go to the Agostino Progression monoblocks you will get tight bass that is unbelievably controlled, and you will probably be impressed at what your excellent speakers are capable of. But the Progressions are Class AB, so you will not have that pure Class A sound. There is a cost for the dynamics and such, and no amp is perfect.

So it really depends what you want, and what is important to you. You could try to have it both ways and get a Pass X600.8, which is more than equal to the Progressions, and has like 50 watts Class A into 8 ohms, and maybe like 100 watts into 4. They sound great, but these are really hard to find used however. I have looked.

I was confronted with a very similar scenario, with my Scala Utopia Evo. I loved the sound driving with a Pass XA160.8, it was heavenly. But the Scala's also present a very challenging load in the bass region, with both low impedance and the electrical phase angle, like your Sasha's. I wasn't getting everything in the bottom I knew was there.

However, after having them a year I realized that I had forgotten that they were able to be bi-amped. I took off the jumpers and let the mid/tweets run on the XA160.8s. I still had my previous amps, Pass X600.5s, which are like 600 watts into 8 and 1200 watts into 4 ohms. I put those on the bottom driving the woofers. They have the same gain, match perfectly. Desmond was very helpful of course, and this is what I am running right now.

It's total nirvana. Astoundingly tight and deep bass, that I can't believe the Scala's were even capable of. The mids and highs, totally separate and driven with the XA160.8 under no stress sounds incredible. I went and relistened to all my old standards and was blown away. It's just nuts good.

The only issue is I am now running two rather large monoblocks per side, and the whole thing eats like 900 watts a side. But I am happy as hell with the sound and don't see how I can improve it at this point.

I hope this helps you understand where you are and what your contemplated amplifier change would do. It's up to you and depends on what you like. If you like the Pass sound, as I do also, you may want to find a X600.5 or better a X600.8 to run the Sasha's and get closer to what you are hearing now.
 
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analogsa

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Apr 15, 2017
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You could try to have it both ways and get a Pass X600.8, which is more than equal to the Progressions, and has like 50 watts Class A into 8 ohms, and maybe like 100 watts into 4.

Sadly, the oppressive laws of physics insist that if an amp can raise 50W class A in 8ohms there are only 25W class A in 4 ohms and 12.5W in 2ohms. Usually there are plenty more watts available but those are no longer class A watts.
 

Jpspock

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Dec 26, 2018
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I am surprised. I had a xa100.5 and than moved to xa160.5 to drive Sasha and now DAW. You can obtain a very tight, articulated bass. I listened to Momentum many times, yes they are faster, but never had the feeling they give better bass. Concerning mid and high, you know who is the winner…
 
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alfa100

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Aug 29, 2014
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South Africa
All the above are excellent replies. I’ve decided to keep my 100.8 for and will upgrade to a more powerful Pass Labs amp later
 

cjf

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Nov 19, 2012
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Sadly, the oppressive laws of physics insist that if an amp can raise 50W class A in 8ohms there are only 25W class A in 4 ohms and 12.5W in 2ohms. Usually there are plenty more watts available but those are no longer class A watts.
According to PASS Labs documentation, this would be incorrect for their XA .8 Mono Blocks.

The XA60.8's that I own double their 8ohm Class A rating (60w) into 4ohms (120w). Not sure about 2ohm as its not listed.
 

Alrainbow

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Dec 11, 2013
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According to PASS Labs documentation, this would be incorrect for their XA .8 Mono Blocks.

The XA60.8's that I own double their 8ohm Class A rating (60w) into 4ohms (120w). Not sure about 2ohm as its not listed.
I’m sorry but this is not as you think . Class ab doubles as imp halves but to stay in class a as imp halves the class a watts also halves
it has to do with maintaining the bias to be on always
 
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cjf

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Nov 19, 2012
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I’m sorry but this is not as you think . Class ab doubles as imp halves but to stay in class a as imp halves the class a watts also halves
it has to do with maintaining the bias to be on always
Apparently Pass is using fuzzy Math's in their product Spec sheets then when it comes to the actual ratings of their Amps in terms of Class A output. Most folks know they are well underrated in terms of total output power but I do see they are no longer mentioning/listing the term "Leaves Class A" like they used to in the Spec sheet of the older models.

They show the Leaves Class A value for the XA .5's and other older models. Somehow the previous model (XA60.5) of my own Amp's (XA60.8's) is shown to double its Class A output from 60w to 122w "MAX" while still being shown as an 8ohm load. Stereophile tested upwards of 375w give or take when in Class A/B mode before clipping. I dont recall if that was into 4 or 2ohms.

I don't know..I can't complain either way. I've only seen the meters move with just a slight "wiggle" in my own rig ever since I started using a digital x-over of 60hz applied to the Magico bass drivers and room correction with subs.

Doing this has no doubt given the Amp a new pair of shoes so to speak since they are no longer wasting a bunch of energy driving the woofers like they use to. My own speakers are absolute pigs to drive and Magico seems to have jokingly given them a 4ohm rating anyway but despite that the baby Pass Amps just shrug it off like a fly so in the end I guess I shouldn't care either way.
 

awsmone

Well-Known Member
Apr 6, 2014
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Canberra Australia
My own 2 cents is try a pair of Lamm m1.2 you can adjust the bias for the impedance for low impedance speakers
i have Alexia 2 and the bass is amazingly good
 

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