Thanks for that AnthonyA.
I intend building both the USSA 5 and also the FSSA. My main speakers are Sonics by Joachim Gerhard and my main listening is to classical (small scale). I also have a Bonsai NX and an ASTX (smaller version). Both do everything but were experimental builds by AndrewT (R.I.P) but both require extensive work...probably new power supplies. At the moment I am using an old Warfdale integrated - which is surprisingly good. But I want to get a build going of my own for self satisfaction!!
But I do like the Maggies...very relaxing but soak up a lot of drive force and a bit 'veiled' hence the idea of the FSSA.
I intend building both the USSA 5 and also the FSSA. My main speakers are Sonics by Joachim Gerhard and my main listening is to classical (small scale). I also have a Bonsai NX and an ASTX (smaller version). Both do everything but were experimental builds by AndrewT (R.I.P) but both require extensive work...probably new power supplies. At the moment I am using an old Warfdale integrated - which is surprisingly good. But I want to get a build going of my own for self satisfaction!!
But I do like the Maggies...very relaxing but soak up a lot of drive force and a bit 'veiled' hence the idea of the FSSA.
Brianco no problem..
Classical!... Ok follow BOM..and may I suggest fssa1 2013 /313 types. It have better depth.. And clarity
As much as I love carbon resistor for its sexy sound...
Those Dale resistors are da bomb when it comes to neatness and palpability /clarity... My usspa1 have those. The tone is more suitable for classical. I listen to them alot cause I got one best buddy (with outrageously expensive gears} who is grazzzy over classical, I got my education from there, have fun building them
Classical!... Ok follow BOM..and may I suggest fssa1 2013 /313 types. It have better depth.. And clarity
As much as I love carbon resistor for its sexy sound...
Those Dale resistors are da bomb when it comes to neatness and palpability /clarity... My usspa1 have those. The tone is more suitable for classical. I listen to them alot cause I got one best buddy (with outrageously expensive gears} who is grazzzy over classical, I got my education from there, have fun building them
Thanks Anthony, I know in which direction to point now 
Indeed, I need current and not voltage, as reasonable power /listening levels, so low voltage but high bias to max Class A, that's the intention
Waiting for Fab's green light, whenever, as no real time constraint on my side, so no stress for Fab... it is just that I am considering it for a while and I read all this like a kid making its Xmas list and waiting for Dec
Your Amp as still the 24dB voltage gain and 22k input impedance?
Thanks again for sharing all this
Claude
Indeed, I need current and not voltage, as reasonable power /listening levels, so low voltage but high bias to max Class A, that's the intention
Waiting for Fab's green light, whenever, as no real time constraint on my side, so no stress for Fab... it is just that I am considering it for a while and I read all this like a kid making its Xmas list and waiting for Dec
Your Amp as still the 24dB voltage gain and 22k input impedance?
Thanks again for sharing all this
Claude
Glad to be of helpThanks Anthony, I know in which direction to point now
Indeed, I need current and not voltage, as reasonable power /listening levels, so low voltage but high bias to max Class A, that's the intention
Waiting for Fab's green light, whenever, as no real time constraint on my side, so no stress for Fab... it is just that I am considering it for a while and I read all this like a kid making its Xmas list and waiting for Dec
Your Amp as still the 24dB voltage gain and 22k input impedance?
Thanks again for sharing all this
Claude
100k input..
Gain... Ask Fab.. But it's pretty good gain as I don't even need a preamplifier. I think mine is a touch lower gain as a little more feedback. It will go as loud as you can take.. I like listen at high level
Building both... That will cover all bases
. It will definitely be a success I'm sure knowing Fab... He is a perfectionist.. I drive him up the wall sometimes lol.
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Nope... Pinnocchio did.both .I think 2 others
I don't really need symetry class A for my main listening . Had a fair share of it and know the difference. I only need a small single ended 10w class A or tubes for my jbl l166/Yamaha ns 10 m in the living room, with the softness... I don't disturb other family members.{that's the advantage!}
In my room... I want a Godzilla.
High bias class Ab babeh.. Bread and butter
I don't really need symetry class A for my main listening . Had a fair share of it and know the difference. I only need a small single ended 10w class A or tubes for my jbl l166/Yamaha ns 10 m in the living room, with the softness... I don't disturb other family members.{that's the advantage!}
In my room... I want a Godzilla.
High bias class Ab babeh.. Bread and butter
And what were your findings between FSSA 1 and 2?
Oh, and how would you rate USSA 3 and 5 with the 2 FSSAs?
Good to have your POV to enable a perfect choice with all these Fab amps around, LOL!
Claude
Based on some questions I had see below some facts about the FSSA.
Even if it meant be up to about 120Wrms into 8 ohms and much more power into 4 ohms, the power can be lowered without compromise to about 30Wrms like I did for my FSSA2 amp. Simply reduce power supply psu voltage accordingly to even +/-30 Vdc or so. However, the bias should still be >= 400ma (double die mosfet) to not compromise the sound. This will allow to use smaller heatsinks.
If you use lower psu voltage and increase output bias current then you can do as AnthonyA and get more class A operation to few watts in 4 ohms and double class A power into 8 ohms speakers resulting in CLASS A listening for most listening moderate level sessions.
Fab
Even if it meant be up to about 120Wrms into 8 ohms and much more power into 4 ohms, the power can be lowered without compromise to about 30Wrms like I did for my FSSA2 amp. Simply reduce power supply psu voltage accordingly to even +/-30 Vdc or so. However, the bias should still be >= 400ma (double die mosfet) to not compromise the sound. This will allow to use smaller heatsinks.
If you use lower psu voltage and increase output bias current then you can do as AnthonyA and get more class A operation to few watts in 4 ohms and double class A power into 8 ohms speakers resulting in CLASS A listening for most listening moderate level sessions.
Fab
Higher bias = more bloom rich fluid and smoother less switching class a.. But it is softer . Less leading edge
Higher voltage = more headroom, punch..lower bias more switching making it more grunt
The medium amount of feedback coupled with dual die of fssa will give more "excitement" and headroom. But with lower volume presume class a..
Ussa will sound more soft and bloom, maybe even a touch bigger image and vocal with all volume.. Plushy softer bass.. But there is also some factor of class ab with low impedance speakers...
Class a and class ab difference..more class a or class ab
So class a would sound more relaxing.. And say you want to listen them with friends and spouse while chatting.. More comfort.. Vocal is more sexy breath into your ears
But high bias class ab will be more suitable if... You want to show off your audio or like to listen to hard rocks.. Audiophile music bash and smashes real sounding kick drums, while still quite bloomy sexy midrange.. Fab class ab special
Higher voltage = more headroom, punch..lower bias more switching making it more grunt
The medium amount of feedback coupled with dual die of fssa will give more "excitement" and headroom. But with lower volume presume class a..
Ussa will sound more soft and bloom, maybe even a touch bigger image and vocal with all volume.. Plushy softer bass.. But there is also some factor of class ab with low impedance speakers...
Class a and class ab difference..more class a or class ab
So class a would sound more relaxing.. And say you want to listen them with friends and spouse while chatting.. More comfort.. Vocal is more sexy breath into your ears
But high bias class ab will be more suitable if... You want to show off your audio or like to listen to hard rocks.. Audiophile music bash and smashes real sounding kick drums, while still quite bloomy sexy midrange.. Fab class ab special
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Oh yea.. Fssa and fssa 2
With my experience building usspa 1 and 2.. The diff between mosfet and darlingtons
Probably very similar...
Fssa1 clearer, more clarity depth wise. less grunt. Smoother airier by a touch..
Fssa darlington more texture. Bass, heavier..intimate tone more fleshy.. It is more 80 90 sound if u know what I mean
I would chose them depending on room and what you like to listen.. Smaller room... Say mid field listening... I suggest 2..
Big room mid to far field listen, more acoustic, classical music types, more looking for hi end accuracy.. Choose 1
See which one fits more... Chose that one
With my experience building usspa 1 and 2.. The diff between mosfet and darlingtons
Probably very similar...
Fssa1 clearer, more clarity depth wise. less grunt. Smoother airier by a touch..
Fssa darlington more texture. Bass, heavier..intimate tone more fleshy.. It is more 80 90 sound if u know what I mean
I would chose them depending on room and what you like to listen.. Smaller room... Say mid field listening... I suggest 2..
Big room mid to far field listen, more acoustic, classical music types, more looking for hi end accuracy.. Choose 1
See which one fits more... Chose that one
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I find FSSA1 more in line with USSA3 but the USSA3 is much higher in Class A, less power. If you have high efficiency speakers, then 30W is way sufficient. I remember when Fab brought his FSSA 1 & 2, I kept them for two weeks. It was not an easy choice but then I decided to build the FSSA2. I can't remember the differences since it was too long ago but the FSSA2 was more to my personal taste.
Now I alternate amplifiers depending on my mood...
All the best!
Do