[qboogie]

Surprisingly, there has not been an official thread for this amplifier even though it has been out since 2018 and remains a TOTL solid-state.

About the XIAUDIO Formula S
Specifically designed for Abyss' high-performance AB-1266 planar headphone series, the Formula S enjoys near-universal praise when the two are paired. It is capable of driving other demanding cans and happens to be a favorite among owners of another famously demanding planar: the HIFIMAN Susvara.

Upgrading to the Powerman external high current power supply has been said to lower the noise floor, improve dynamics, weight, and image separation. So complimentary are the two that the Formula S amplifier is hardly ever recommended without it. It may be for this reason that JPS does not even bundle an IEC power cord with the Formula S.

Some helpful reviews:

https://headfonics.com/xi-audio-formula-s-review/
https://audiobacon.net/2018/07/04/eleven-xi-audio-formula-s-headphone-amplifier-and-powerman-review/
https://www.head-fi.org/showcase/xiaudio-formula-s.22675/reviews#review-19879
https://www.head-fi.org/threads/rev...r-includes-large-high-end-amp-roundup.886668/ [edit: scroll down to the Formula S section]

Check the Abyss site for details:
https://abyss-headphones.com/collections/abyss-electronics/products/eleven-audio-xiaudio-formula-s

 

[jlbrach]

long, long overdue..a great amp especially with the powerman which makes it special

 

[Slim1970]

Nice to finally have a place to talk about this great amp, thanks @qboogie

 

[DJJEZ]

How does this compare to a WA33? Got my eyes on both

 

[jlbrach]

I think it is a tube vs SS decision...cant go wrong with either,I have heard the WA33 but have lived with the formula s/powerman......

 

[mammal]

How does it compare to bakoon amp13r? Has anyone tried/owned both?

 

[jlbrach]

I own both...they are both fantastic...i would say the bakoon is slightly better with the susvara and they are pretty much equal with the abyss...both so good thats the best I can do

 

[leilei787]

Is it a significant step up from violectric v281? Is it worth the $2K spent? Thanks!

 

[mammal]

Which version do you own people? XLR or RCA? I read that Formula S is single ended by design, so why would you chose XLR over RCA? I guess only if your DAC did not have RCAs out (like Mola Mola Tambaqui) or am I missing something? Thanks!

 

[jlbrach]

Is it a significant step up from violectric v281? Is it worth the $2K spent? Thanks!

I owned the 281 and to my ears there is no comparison...in terms of xlr vs SE on the formula s it makes no difference since it isnt balanced it sounds the same out of both...I have never heard a difference but it is nice to be able to use whatever cable you have..I repeat it needs the powerman in order to truly shine

 

[tunes]

Is it a significant step up from violectric v281? Is it worth the $2K spent? Thanks!

I see you have a DNA Starlett. I am trying to decide between the Starlett and Quiksilver tube amps fir my Utopias.

 

[FLTWS]

I've always preferred my Formula S & Powerman with my Phi CC's over my other possible amp combos. I just moved my HSA-1b to my second rig to go head to head with my F/S&P in the near future. The 1266 Phi with CC pads has always struck my ears as a very full bodied sound and the F/S&P has a clean delivery that I think compliments it well. The HSA-1b is a bit warmer or richer sounding amp and I've just spent over 2 months with it and the SR1a and Senn 800 and 800S, so I'm looking forward to the side by side comparison.

Now if Abyss would offer an upgrade or trade-in program to go from Phi CC to TC... but they are selling TC's like hot cakes based on current delivery dates being posted for here for new purchasers, soooo I won't be holding my breath.

 

[tunes]

I've always preferred my Formula S & Powerman with my Phi CC's over my other possible amp combos. I just moved my HSA-1b to my second rig to go head to head with my F/S&P in the near future. The 1266 Phi with CC pads has always struck my ears as a very full bodied sound and the F/S&P has a clean delivery that I think compliments it well. The HSA-1b is a bit warmer or richer sounding amp and I've just spent over 2 months with it and the SR1a and Senn 800 and 800S, so I'm looking forward to the side by side comparison.

Now if Abyss would offer an upgrade or trade-in program to go from Phi CC to TC... but they are selling TC's like hot cakes based on current delivery dates being posted for here for new purchasers, soooo I won't be holding my breath

Please share your comparison between HSA1b with Phi CC versus Formula S & Powerman since I have the HSA1b and SR1a now and may eventually get a used Susvara or Abyss.

 

[qboogie]

I think it is a tube vs SS decision...cant go wrong with either,I have heard the WA33 but have lived with the formula s/powerman......

I did a search for the terms powerman and formula S on head-fi and found that more than half the mentions came from you. Abyss should give you a little cut of the profits for your promoting their gear

 

[jlbrach]

I would like that,perhaps you can arrange it