Tubes Asylum: REVIEW: Audio Prism Audio Prism Mantissa Preamplifier (Tube) by F. Sonic Smith

I ordered my AP Mantissa sound unheard after auditioning several solid state preamps to replace my McCormack TLC-1. The rest of my system consists of B+W M805s augmented bass-wise with JPS Labs Golden Flutes fed
electrons by a McCormack DNA.5 fully modded by SMcAudio. Cabling is JPS
Labs Superconductor ICs and LAT biwire. CDP is a Classe CDP.5. No vinyl in my system.
I wanted more dynamics than I was getting with my TLC-1 which I attributed
to it being passive (in disposition and circuit). I didn't want to give up
the tremendously wide soundstage and transparency I was getting with the TLC-1. When Steve McCormack told me he had some "fantastic" upgrades in mind for the TLC-1, I figured my search was over since his mods to the original DNA.5 Deluxe were absolutely stunning. Well, the SMcAudio TLC-1
Steve loaned me didn't wow me. Dynamics came and transparency went out of
my system.
I read a review of a strange product called an Audio Prism Mantissa from a
guy who had a system pretty similar to my own. He had replaced a TLC-1 too.
I had been planning on auditioning an AI M3a which was going to require a
mail order source since there is no local dealer in Cols. OH. I found out
Galen Carol in San Anton(e) TexAss was a dealer of both, and knowing of his impeccable reputation sought his opinion. Lets just say Galen was very
positive about the Mantissa while being politically savy enough to not specifically state that it was better than the AI M3a (and maybe it isn't).
I have now had the Mantissa in my system for six weeks. My small B+Ws sound as though aliens descended in the night and inbred my minimonitors with good electrostats. The soundstage is seamless and image sizes are larger. Transparency is greater, with more microdynamics. How can this be? Galen told me he believes "tube magic" is due to tube-induced phase shifts. I don't profess to know or care. Soundstage width is just as wide as it was before but now I (I mean my system) has real depth as well. The
dynamics I wanted are abundant, but I also got far better microdynamics, which I have come to realize are just as, if not more, important.
The Mantissa comes supplied with NOS JAN Philips 6922s and 12AU7s. I liked this combo but after three weeks couldn't resist putting in Tungsram
6DJ8s and Mullard ECC82s recommended by Kevin Deal of Upscale Audio (a great guy to deal with). The latter combo gives a bit of sugar to female vocals and adds punch to bass with more extended highs.
Regarding build and esthetics, I had no trouble whatsoever getting used to the dual attenuators. Reality is (at this stage of human evolution) that anything other than attenuators with one resistor per channel in the circuit path at any time involves a compromise I'm not willing to make, so remote be damned. I was prepared for a visual let-down based on AP's brochure, but the unit in black looks pretty cool in real life. The outboard power supply is massive and attaches to the preamp with a garden hose-like cable.
I'll end with an example of what the Mantissa brings to my system. I always thought Bill Frisell's "Nashville" sounded dry in comparison with his subsequent release, "gone, just like a train". I put in "Nashville" while I was still breaking it in, with maybe thirty hours of play time.
Within seconds, I put down the magazine I was reading, and realized that
"Nashville" was harmonically rich and vibrant after all. I loved every minute of the disc for the first time. Amazingly, "gone, just like a train" does not sound syruppy now, and now both discs sound equally good. How can this be? Must be phase shift.
I don't claim the Mantissa is superior to any other similarly priced tubed preamp in my system or yours. Again, I did not audition the AI M3a. I only know that it is a great product that has transformed my system. Your mileage may vary.

REVIEW: Audio Prism Audio Prism Mantissa Preamplifier (Tube) Review by F. Sonic Smith at Audio Asylum