[aceinc]

I built a pair of speakers and based on my best calculation, they appear to have ~97 db sensitivity. So my 200w amplifier, which sounds great, is a bit of overkill. A friend popped by with a 3 watt triode amp and it sounded good. I was wondering if anyone had experience with the Chi-Fi Class A amps sold on Amazon, eBay, AliExpress, etc. If so, which would be worth a listen to?

Some useful info;

I am running the woofers below 80hz on their own amps.
I have the mid-woofers high passed at ~140hz 1st order.
The speakers are very revealing and dynamic.
They have exceptional soundstage.

I suspect something in the 10-20w range should drive them well. To get a feel for the sound, imagine the dynamics of horns without the horn coloration.  I also have a pair of Klipsch Cornwall IIIs, so I speak with a little knowledge about horns.

[JakeJ]

Hi Ace,

I bought and use one of these for my desktop sound system.  Very refined sound overall with punch.  I'm using PMC DB1 Gold studio monitors which are 87dB/1W/1M, nearfield of course, and it can get too loud.  I got mine a couple of years ago so it was less expensive but only $30 or $40.

Now if you want to get serious you might look into the Pass Aleph 5 clone.

[davidldl]

I've seen a bunch of reviews on youtube and they do sell this one on Amazon. This is supposed to be a clone of the Musical Fidelity A1.    It is a class A amp.   Some people tweak it by removing the bypassing the volume pots.

video link for volume bypass:   https://www.youtube.com/watch?v=nkxfpDr2su4

Cost on amazon $269.00
https://www.amazon.com/dp/B0DN5R48RN


David

[FullRangeMan]

IMO with the latest Class D and GaN-FET amps Class A or A/B Transistors amps are obsoleted, due the high heat, price and low power, but if you make question use Class A Transistor amps check the MoFo 20W power amp, an audiophile Single Ended minimalist project with only 1 output Transistor, it need an pre-amp with hi gain.
Our AC member poseidonsvoice had made some units of this amp.
https://www.audiocircle.com/index.php?topic=179626.msg1887792#msg1887792

Or you can go the modern way with the new SMSL GaN-FET amps:
SMSL PA200, 85W, 8Ω, $419, remote volume control
https://shenzhenaudio.com/collections/speaker-amplifier/products/s-m-s-l-pa200-speaker-amplifier

SMSL PA400, 200W, 8Ω, $555, remote volume control
https://shenzhenaudio.com/products/s-m-s-l-pa400-power-amplifier?_pos=2&_sid=e9eb9eb60&_ss=r

[steve k]

Try https://classdaudio.com/. High build quality, great sound and powerful.I've been using the monoblock pair to drive Maggie LRS + for over a year now with no complaints. Much cleaner sound than the Schiit amp I used previously.
Steve

[AllanS]

Try https://classdaudio.com/. High build quality, great sound and powerful.I've been using the monoblock pair to drive Maggie LRS + for over a year now with no complaints. Much cleaner sound than the Schiit amp I used previously.
Steve

Which Schiit amp are you referring to?  I was going to suggest a used Aegir 1 which I like with my 90dB 4 ohm M4 Sapphires.
https://tmraudio.com/fresh-arrivals/schiit-audio-aegir-stereo-bridged-mono-power-amplifier/

But I’d forgotten about the Class D Audio Mini GaN 5 that created quite a stir around here a few years ago.  I was tempted at the time to give them a go but ended up going a different direction.

https://classdaudio.com/product/mini-gan-5-2-ch-balanced-amplifier-upgraded-to-6-5/
https://www.audiocircle.com/index.php?topic=183099.0

[steve k]

Schiit Vigar. This was my review at the time:

 Rated 5 out of 5

Verified Customer – December 8, 2025

Keith Herron came by tonight to audition your mono blocks with another couple friends. He was impressed. He said the sound was very transparent and not as “thick” as my old amp—the Schiit Vidar. He really liked it. We listened to all sorts of digital and vinyl sources—classical, pipe organ, jazz, female vocals, they all sounded great. Congrats! It’s ironic. Keith is definitely old school but you’ve presented him with the future and he respected that.

[planet10]

All SE ampas are Class A. No tube kit under a grand will compete with Nelson Pass’ ACA(SE) or ACAmini (PP). I prefer the latter, it has sufficent power for your requirements.

What doe the imedance of your speaker look like? Small SE tube amps prefer a flattish impedance.

dave

[aceinc]

All SE ampas are Class A. No tube kit under a grand will compete with Nelson Pass’ ACA(SE) or ACAmini (PP). I prefer the latter, it has sufficent power for your requirements.

What doe the imedance of your speaker look like? Small SE tube amps prefer a flattish impedance.

dave

I do not have the knowledge on how to measure the impedance of my speakers. I may or may not have the tools needed. The last time I saw a description of how to measure impedance using REW, it seemed to require a sound card and and looping back the speaker output using a resistor into the input of a sound card.

[rojo]

you should try to make your own. It's not that difficult, and actually pretty affordable. Lots of kits out there.

[pboser]

Planet10 said: “All SE amps are Class A. No tube kit under a grand will compete with Nelson Pass’ ACA(SE) or ACAmini (PP). I prefer the latter, it has sufficent power for your requirements.“

Hi Dave – hope you are well. Do you mind elaborating on why you prefer the mini? I’ve built too many’s and enjoy them, but I’ve been curious about whether the single ended earlier version would be superior.

Thanks, and take care,
Pete

[Rusty Jefferson]

Is your friend's triode amplifier home built (diy) by himself or a local friend? There are a lot of folks designing and building their own single ended and push/pull tube amplifiers that sound great and cost less than commercial. I see you're located in south Florida so I can't introduce you to the builders in my area, but you might find some at diyaudio. If you can get introduced to a group in your area you may be able to hear a variety of different types of amplifiers and learn a few things while you're at it.

[planet10]

Other than it sounds really good? Nelson is a brilliant designer. 6W is pretty much the same power as an SE300Bs 5-8w

dave