I received my Sr1a on Jan 2nd.
Amplifier with more than 100 Watts for 6 ohm is recommended for Sr1a.
But I started with Marantz PM5003 which got a favorable review from Stereophile.
https://www.stereophile.com/integratedamps/marantz_pm5003_integrated_amplifier/index.htmlEven with 50 Watts available at 6 ohm, this one has no difficulty driving Sr1a with crisp high and reasonably tight bass.
But soundstage is not that wide or deep as I had tried with Chord Etude amplifier on last November.
I played "Autumn Leaves" sung by Eva Cassidy, " I am so lonesome tonight" by Elvis Presley
"Sound of the West and William Tell Overture " in Roundup Telarc CD and Schumann Piano Trio played by Pierre Fournier, Henryk Szeying. Arthur Rubinstein.
Also I played some old K pops that I am familiar with.
I used ripped CD's stored in SSD of Cocktail Audio X30 and Dac is Chord Dave and HMS.
Then I played same list of music using Rogue Cronus Magnum II fitted with Nos Telefuken 12Ax7 and Amperex 12Au7 (100Watts for 8 ohm)
Now Sr1a really sings with wide and deep soundstage with more refined treble.
This amp seems to work with Sr1a very well.
Then I moved to Crown XLS 2502 (This one has 775W for 4 ohm ).
I got this one to drive two 18 inch subwoofers of Scaena 3.2 speakers.
Wow this PA amp impressed me with lot of headroom and snappy transient but without hard edge.
Of course, Rogue sounds sweeter than Crown but latter does sound neutral not on the dry side.
I went back to Stax 009s driven by Kgsshv Carbon amplifier to play same list of music for comparison.
Stax give more relaxed and nuanced details although the absolute amount of details are on par with each other.
But Sr1a give much faster and open sound reminding me of Apogee Duetta Sig that I had used from 1989 to 1999.
Soundstage width is similar but Sr1a has an edge on depth of soundstage.
I think Raal Sr1a may be the best headphone under 10K$ overall although Stax 009s is musical with relaxed presentation.
Rogue Apollo monoblocks with 250 watts may work better with Sr1a with more headroom.
Also, Schitt will market "Jotuheim R", the dedicated amp for Sr1a forgoing interface early half of this year.
I will try it out with Sr1a after it is released.