I LOVE seeing reference to the classic, overlooked, and largely forgotten AudioPrism Mantissa! I proudly owned and used one for over twenty years. I bought mine new from a prominent Columbus, OH high-end retailer who did not carry Audio Prism and who had never heard of it but was able to order one for me. The outboard power supply and dual mono circuit layout with dual stepped ladder resistor attenuators was classic. I had long conversations with it's designer Victor Tiscareno when it was new.-he could not have been nicer and more generous with his time over the phone to a complete stranger. It's nostalgic to me because the original duo of Victor Tiscareno and Byron Collet were only in business for 6-7 years between '92 and '98 or '99 when Mark Levinson took over the line of preamps and amps and rebadged them with slight modification as Red Rose Music.
My Mantissa faithfully served me well with many hours of enjoyment, primarily with three amps-a McCormack DNA.5 given the 'Full Monty" upgrade by Steve McCormack, a DNA1 also heavily modded by SMcAudio, and an ARC VS110. Solid state or tubed, the Mantissa mated well. It is very easy on the four tubes-mine often went for three years of heavy use before needing to be replaced. Only a month ago, I replaced mine with an ARC Ref 6, a pre that cost 3-4 times more adjusted for inflation. The Ref 6 affords a more expansive soundstage and more detail, but the differences are largely in character as opposed to qualitative. The Mantissa was that good. Be sure to clean the rotary switch contacts at the rear of the pre with some isopropyl alcohol as they are prone to oxidation which affects SQ. I have zero knowledge about the other pre you mention, but the Mantissa is a great pre that is well built and reliable.
