Hi, I own the Nagra (with a Nagra VFS). It's a excellent match with Lyra cartridges. I've used it with a Helicon, Skala, and now a Atlas. It's very revealing of loading and allows you to really experiment with various gain. The tubed gain section is always on +34db. Then you can jumper in Nagra wound transformers +11db and a solid state stage +15db. So a total of 60 db. I've gone through the various combinations seeming a 100 times. The tube+step up trans seems to be the most natural...Tube+SUT+SS adds tightness/extension to the extremes and lowers the noise/increases the dynamics and most even frequency response. I am still playing with the Tube+SS (not SUT)...The Atlas has enough output to allow this for me...
I also have the MM 2nd input installed and have used the Nagra Tube only with external higher gain SUT. (EAR MC4) excellent results here to...with a Allaerts MC2 Finish cartridge or my Lyra Atlas. For the Lyra Atlas, I seem to prefer the Nagra MC input, SUT+Tube+SS (my preamp is low gain only +6db so your milage may vary here)
I've owned this phono stage for over 6 years. It's the oldest component in my system. I have directly compared it to ARC Ref 2SE, Boulder 1008, Allnic H300v, and BAT VKP10SE superpak (which I had owned before I bought the Nagra.
-The ARC has a bigger stage, tigher bass, ...but I am not a fan of the 6h30 tube and the Nagra's sweetness just won out for me...
-The Boulder is VERY good...shockingly so...will make you really think...I couldn't believe I was digging a ss phono vs tubes....but I had to change all my cables for XLRs and this slowed me down here
-The BAT lost on the Nagra's incredible transparency and a zillion color's textures in the music...my toes were tapping more...and a much better portrayal of the top end...that sweetness and extension....I've always been a fan of the 12ax7 tube...it shows here...
-The Allnic H300v is a another tough one. It's very good...better portrays space and even more texture/depth in the bass. But from the midrange up the Nagra was clearly more resolute and possesses more transparency and clarity. The Allnic seemed "dark" side by side. I will say I've heard the Allnic in a several systems and I NEVER thought those systems were dark.
I've also ran the Nagra via a Redwine Audio Black Lightning battery vs the Nagra power supply. You loose some dynamics/resolution...but gain a little in sweetness. It's a tough call on which way to go...system matching may dictate what's best for you.
A few final comments...the Nagra is VERY quiet for a tubed phono stage. Adding the Nagra VFS is crucial for top performance. I'm using the Nagra with a 25k table, a 10k arm, a 9.5k cartridge and 11k interconnects to a 30k preamp. It is NOT outclassed. It fits right in...
(Drunkenrabbit...on some of the Nagra gear like their pyramid amps (can't remember the model) had a cooler disposition...the VPS is ever so slightly warm and sweet like the Nagra PLL I used to own at least my opinion in my system with my ears ;-)