NAT preamps have a full bodied muscular sound but not a sweet fuzzy sound. Dynamics on the NAT Plasma I had were huge and soundstage was deep and wide. Great preamp actually. It was also true dual mono including the tube rectification and tube regulation it had in the power supply. One of the few pieces I wish I had kept.
Aries Cerat also has a very robust, bottom up, structural sound that also happens to have explosive dynamics with tons of resolution and detail as well. The sound is so stable that you probably never realized it was not totally stable before you hear it with an AC preamp.
I also had and loved an amazing Silvaweld SWC1000 preamp, which ultimately was on the sweeter end but damn it sounded good.
It is neither tubey warm nor solid-state dry; if it has a leaning it is just a wee bit toward the sweet, with meat on the bones. Those are audiophile words. If you know the sound of different acoustic instruments -- from the wet breathy grunt of a baritone sax, to the brassy rasp and growl of a lower octave trombone, to the attack of bow on cello string through the duration of its bloom to its dying resonance after lift -- the LL1.1 Sig offers the loudness, pitch and timbre representative of how the instrument is played by its performer.
For many people the lack of a remote control is a dealbreaker. It is not a dealbreaker for me.
For me it is a bit problematic that the Lamm LL1.1 Signature is a single-ended only design, and the Io sounds best using its balanced output. (The LL1.1 Signature has an XLR output connector, but it is "balanced" with only a transformer, and not with a true differential circuit.)
I think the output impedance specification of 16,500 ohms is a typo.
The Jadis, also, is single-ended only, with no remote control.
I had the incito in for a demo... it is a great value pre .. a friend has the impera ref .. I would say there is quite a step up at each level .. considering the usual law of diminishing returns.
This is particularly the case for "full bodieness" ... orchestral music has more of that low end power that you hear live
If you have an opportunity to demo them it's worth the effort
For me it is a bit problematic that the Lamm LL1.1 Signature is a single-ended only design, and the Io sounds best using its balanced output. (The LL1.1 Signature has an XLR output connector, but it is "balanced" with only a transformer, and not with a true differential circuit.)