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Parasound 2125 V.2 Amplifier Review

Rate this amplifier:

  • 1. Poor (headless panther)

    Votes: 37 20.6%
  • 2. Not terrible (postman panther)

    Votes: 114 63.3%
  • 3. Fine (happy panther)

    Votes: 27 15.0%
  • 4. Great (golfing panther)

    Votes: 2 1.1%

  • Total voters
    180

amirm

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This is a review and detailed measurements of the Parasound 2125 V.2 power amplifier. It is on kind loan from a member and costs US $899.
Parasound 2125 V.2 Power Amplifier Review.jpg

The 2125 has an understated look with just a few touches to keep it from looking boring. The only controls in front are for which set of speakers it drives. There is more however in the back:
Parasound 2125 V.2 Power Amplifier back panel Review.jpg


For those of you wanting to use it with a sub, it has selectable high pass filter of 20 or 40 Hz. Trigger is supported as well as bridging.

Parasound 2125 V.2 Measurements
I had a heck of a time getting stable ratings in the dashboard with channel 1 mostly going nuts on its own. I thought this was a grounding problem so tried many things. There was hardly a difference. It was not until the power measurements that I realized something is going on the amp in the 5 to 20 watt range. Anyway, here is our dashboard when both channels were behaving:

Parasound 2125 V.2 Power Amplifier Measurements.png

Measured noise+distortion lands the 2125 above average ranking:

best stereo amplifier review.png

best stereo amplifier zoomed review.png


Noise performance is not great at 5 watts but naturally improves at full power:
Parasound 2125 V.2 Power Amplifier SNR Measurements.png


Multitone reflect the average distortion rating:
Parasound 2125 V.2 Power Amplifier Multitone Measurements.png


Frequency response is very good:
Parasound 2125 V.2 Power Amplifier Frequency Response Measurements.png


I was however surprised that gain dropped when I activated the high-pass filters.

As noted, my first power sweep had instability in mid power. I thought this was instrumentation error so I filtered the heck out of it and got these:
Parasound 2125 V.2 Power Amplifier Power into 4 ohm Measurements.png

Parasound 2125 V.2 Power Amplifier Power into 8 ohm Measurements.png


On reflection though this was amplifier instability as we can see when I sweep the frequency:
Parasound 2125 V.2 Power Amplifier Frequency vs Power into 4 ohm Measurements.png


There is a frequency dependent hump in distortion which is very strange. It is likely due to some kind of voltage rail switching.

There is a lot of power available though in a cool running case:
Parasound 2125 V.2 Power Amplifier Max and Peak Power into 4 ohm Measurements.png


Conclusions
This kind of performance would usually garner my recommendation for the 2125. On reflection though, I am worried about increased distortion in the "sweet" area of power band -- 5 to 20 watts. Company needs to work on mitigating this issue. So for now, I won't be recommending the Parasound 2125 even though it checks many boxes from value to functionaltiy.
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As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 

Highmodulus

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Is this a used amp?

My amp. Purchased new. Installed in a large theater, bridged into a 4ohm Triad Gold LCR. I have / had 8 of these in the rack. 3 bridged to the LCR channels and 5 running wides/surround/overhead. Felt the LCR was missing some sparkle/sound so I switched to a Nord Acoustics 3 channel running Hypex 500MkII units for the LCR. I gained a lot of clarity and crispness in the high end with the Class D over the Class A/B Parasound. Will swap other channels as $ permits.
 

beagleman

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Is this a used amp?

My amp. Purchased new. Installed in a large theater, bridged into a 4ohm Triad Gold LCR. I have / had 8 of these in the rack. 3 bridged to the LCR channels and 5 running wides/surround/overhead. Felt the LCR was missing some sparkle/sound so I switched to a Nord Acoustics 3 channel running Hypex 500MkII units for the LCR. I gained a lot of clarity and crispness in the high end with the Class D over the Class A/B Parasound. Will swap other channels as $ permits.
When you say gained a lot of clarity and crispness in the high end, what do you attribute to being changed actually??
 

Highmodulus

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Though I am scratching my head. Parasound lists 2x225W @ 4ohm. My past experience with Parasound was listing RMS power per channel. Based on the results…might be a little bit of marketing here.
 

wemist01

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I love the look of their products, but I had such bad luck with the ZPhono USB that I just can't trust anything that looks similar. The ZPhono was a magnet for hums that were influenced by the location of the device on my shelf. Move it to the left two inches, better. To the right, the hum comes back. Had no such issues when I switched to ProJect. I know that is completely irrelevant for their other products, but still...
 

AndreaT

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Barely competent. Either design or manufacturing QC (or both) are at fault here as the asimmetry of the two channels seems to indicate. Not worth the time to listen to it and the money. A little more buys the infinitely better measuring (and sounding) Hypex-based amplifiers, It seems to me that Parasound either innovates or is directed to the dustbin of hi-fi history.
 
Last edited:

Highmodulus

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When you say gained a lot of clarity and crispness in the high end, what do you attribute to being changed actually??
Only three things changed…amp swap + use XLR now (versus RCA) and rerun Anthem Room Correction. So rewatching the same scenes at the same volume dialog and environmental sounds are much more noticeable and clear. Maybe it is placebo. But I really prefer the sound of the Hypex amps over this traditional A/B unit. Lacking these objective measurements…that’s what we are down to opinions and perception.

But you play a piece of music on a cheap boom box…then play the same piece on a $25,000 2 channel set up. Probably can hear more clarity and depth right? To my ears I hear more depth and clarity in the class D. Best I can tell ya.
 

Cars-N-Cans

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It beats its specifications in terms of distortion and is subjectively transparent, but the performance is more in line with older class B designs from the 80’s. If its the kind of design that is durable and puts up with abuse, I could potentially see it being useful, but at close to $1k and only having moderate amounts of power, it’s not the best value.
 

Cars-N-Cans

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My amp. Purchased new. Installed in a large theater, bridged into a 4ohm Triad Gold LCR. I have / had 8 of these in the rack. 3 bridged to the LCR channels and 5 running wides/surround/overhead. Felt the LCR was missing some sparkle/sound so I switched to a Nord Acoustics 3 channel running Hypex 500MkII units for the LCR. I gained a lot of clarity and crispness in the high end with the Class D over the Class A/B Parasound. Will swap other channels as $ permits.

For what it’s worth it’s likely subjective as the amp‘s distortion products fall below the thresholds of what’s audible. Only if you had them running into a very low impedance load could it have likely had audible distortion. Not that it really matters since you now have the setup you desired, but electronics have to be quite bad for them to become audible. Only real tight spec is noise since it’s heard on its own and gets summed and amplified as it goes down the chain.
 

Highmodulus

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Several folks have messaged me on this. I do find it interesting that it’s bumps in distortion (higher frequencies) and mid power are where I seemed to have noticed the largest improvement? Again could be placebo.

I bought these eight amps on reputation alone. I owned a Parasound HCA-2200mkII years ago. It was a phenomenal piece. Given these results I am not disappointed. But yet I am not happy either. As stated I will be replacing with Hypex amps…just to be sure. LOL
 

Cars-N-Cans

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Several folks have messaged me on this. I do find it interesting that it’s bumps in distortion (higher frequencies) and mid power are where I seemed to have noticed the largest improvement? Again could be placebo.
Those are above 10 kHz. Very little energy out there in normal audio, and to get to those levels, the amp would be near clipping. The power of normal music is typically, more or less, a 1/f relationship. Also its quite typical of class B amplifiers to have rising distortion at high frequencies due to them having less gain margin to reject the 50/60 Hz based ripple from the unregulated supply. Odd that it’s jagged, though. Only linear amp that I have that doesn’t do that is one that has a regulated switching supply. Distortion profile is flat since there’s nothing to reject from the power rails. But noise suffers at around 80-85 dB SNR.

Still it would be interesting to do comparative testing once you have the new class D amps. I would expect there to be no audible difference once they are level matched.
 

solderdude

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Does not make it to it's own power output specification.
That would depend on how much distortion one tolerates. Parasound does not specify distortion at the rated output power.
4Ω seems to be 225W (-40dB = 1%) and 150W at 8Ω are both met and differs 0.7dB compared to power at the knee of distortion (0.03%).
So they don't seem to be lying about output power in their specs.
390W at 4Ω bridged is just 0.1dB shy.

Also the max output power is most likely slightly mains voltage dependent.
 

Jimster480

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Is this a used amp?

My amp. Purchased new. Installed in a large theater, bridged into a 4ohm Triad Gold LCR. I have / had 8 of these in the rack. 3 bridged to the LCR channels and 5 running wides/surround/overhead. Felt the LCR was missing some sparkle/sound so I switched to a Nord Acoustics 3 channel running Hypex 500MkII units for the LCR. I gained a lot of clarity and crispness in the high end with the Class D over the Class A/B Parasound. Will swap other channels as $ permits.
Very cool that we get this here, I appreciate you sending it in!
 
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